Set of pool cleaning robots

ABSTRACT

A method and a set of pool cleaning robots for cleaning a pool. The set includes a first pool cleaning robot and a second pool cleaning robot that differ from each other by at least one unit out of a propulsion unit and a cleaning unit. Each one of the first pool cleaning robot and the second pool cleaning robot includes a filtering unit, a housing, and a controller.

CROSS REFERENCE

This application claims priority from U.S. provisional patent Ser. No.62/393,816 filing date Sep. 13, 2016 which is incorporated herein byreference.

BACKGROUND

Large pools such as Olympic pools and pools of 50 meters or more areusually cleaned with a single commercial type pool cleaner. These typepool cleaners may also be referred to as public pool cleaners that maybe used in any shape type pool. The size of such a pool cleaner mayapproximate 1 meter by 50 by ×50 cm.

Examples of such pool cleaners may be manufactured by the applicant,Maytronics Ltd. For example: —2×2, wave 300 or wave 200. Similar poolcleaners are available from other vendors.

A similar situation exists in the private pool sector whereby a singlepool cleaner is employed in swimming pool sizes of more or less 6 meterby 3 meter or 10 meter by 5 meter and the like that may be used in anyshape type pool. The size of such a pool cleaner may approximate 40 cmby 40 cm by 30 cm.

It is common for pool owners to construct multiple pool basins in a poolcomplex. One large basin may incorporate other basins or a private poolmay integrate a smaller jet hydrotherapy basin or another low waterlevel children pool.

For swimming pool operators, it is of utmost importance to have theirswimming pool in a clean state when the pool is about to be used. Forswimming pools that are businesses, an unclean pool may mean loss ofswimmers who would rather stay away from an unclean pool and this maytherefore mean loss of business to the pool operators or owners.

The cost and the advantages of purchasing and using pool cleaningequipment should be taken into account by said pool owners or operators.

A pool operator concern is related to downtime and after sale service.Namely, if a single commercial pool cleaner needs to be serviced orrepaired, the said owner may remain without any pool cleaning equipmentfor an undefined period of time. This aggravates the pool owner'sconcerns and alternative pool cleaning systems are needed even if for atemporary period of time. The same applies in the private pool sector.

There is a growing need to reduce the human intervention and improve theefficiency of pool cleaners in swimming pools.

SUMMARY

Sets of pool cleaning robots, one or more pool cleaning robots of a set,methods for programming one or more pool cleaning robots and methods forcleaning a pool by a set as illustrated in the specification and/or theclaims and/or the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, a preferred embodiment will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings.

FIG. 1A is an example of a pool and a set of pool cleaning robots;

FIG. 1B is an example of a pool and a set of pool cleaning robots;

FIG. 1C is an example of a pool and a set of pool cleaning robots;

FIG. 1D is an example of pool regions and one or more cleaning paths;

FIG. 1E is an example of pool regions;

FIG. 1F is an example of pool regions;

FIG. 1G is an example of collision avoidance maneuvers;

FIG. 2A is an example of a pool and a set of pool cleaning robots;

FIG. 2B is an example of a pool and a set of pool cleaning robots;

FIG. 3 is an example of pool cleaning robots;

FIG. 1B is an example of a pool and a set of pool cleaning robots;

FIG. 4A is an example of a pool and a pool cleaning robot;

FIG. 4B is an example of a pool cleaning robot;

FIG. 4C is an example of a pool cleaning robot;

FIG. 5 is an example of a pool cleaning robot;

FIG. 6A is an example of a pool and a pool cleaning robot;

FIG. 6B is an example of a pool and a pool cleaning robot;

FIG. 6C is an example of a pool and a pool cleaning robot;

FIG. 7 is an example of a pool and a pool cleaning robot;

FIG. 8 is an example of a pool and a pool cleaning robot;

FIG. 9 is an example of pool cleaning robots;

FIG. 10 is an example of filtering units;

FIG. 11 is an example of a pool and pool cleaning robots;

FIG. 12 is an example of a pool cleaning robot;

FIG. 13 is an example of a pool cleaning robot;

FIG. 14 is an example of a pool cleaning robot;

FIG. 15 is an example of a pool cleaning robot;

FIG. 16 is an example of pool cleaning robots;

FIG. 17 is an example of pool cleaning robots;

FIG. 18 is an example of pool cleaning robots;

FIG. 19 is an example of pool cleaning robots;

FIG. 20 is an example of a user that programs a pool cleaning robot;

FIG. 21 is an example of a pool cleaning robot;

FIG. 22 is an example of a pool cleaning robot;

FIG. 23 is an example of a method; and

FIG. 24 is an example of a method.

DETAILED DESCRIPTION OF THE DRAWINGS

Any reference to a pool cleaner should be applied, mutatis mutandis to amethod that is executed by a pool cleaner and/or to a non-transitorycomputer readable medium that stores instructions that once executed bythe pool cleaner will cause the pool cleaner to execute the method.

Any reference to method should be applied, mutatis mutandis to a poolcleaner that is configured to execute the method and/or to anon-transitory computer readable medium that stores instructions thatonce executed by the pool cleaner will cause the pool cleaner to executethe method.

Any reference to a non-transitory computer readable medium should beapplied, mutatis mutandis to a method that is executed by a pool cleanerand/or a pool cleaner that is configured to execute the instructionsstored in the non-transitory computer readable medium.

The terms “avoidance maneuver” and “avoidance step” are used in aninterchangeable manner.

The term “and/or” is additionally or alternatively.

Pool owner or operator may be provided with a system that may include atleast two pool cleaners available or a set of pool cleaners so that ifthe one is used elsewhere or that it is temporarily non-useable, anotherpool cleaner may continue performing the tasks.

In private pools especially, if the operator chooses to have multiplepool cleaners in his pool (or pools) instead of one, also it would beadvantageous to have a downsized or miniaturized pool cleaner with asize of, as an example only, 20 cm by 20 cm by 15 cm. Other sizes may beprovided. Such a size pool cleaners set will be most suitable in thesaid smaller pools and especially so if at least one of the set is abattery-operated pool cleaner.

There may be provided a set of pool cleaning robots for cleaning a pool.

The set of pool cleaning robots may be configured to clean the samepool. The cleaning may be executed simultaneously (by pool cleaningrobots of the set), in a partially overlapping manner or in anon-overlapping manner. The pool cleaning robots may participate incleaning the pool.

One or more pool cleaning robots of the set may cooperate with eachother—thereby cleaning the pool in a cooperative manner. This mayinclude an exchange of information, commands, maps of the pool,allocation of cleaning tasks, physically interacting, and the like.

An allocation of a cleaning task may include an allocation of a regionof the pool to clean and/or defining cleaning parameters. Any referenceto an allocation of a cleaning task should be applied mutatis mutandisto an allocation of a region—and vice verse.

Using a set of pool cleaning robots may speed the cleaning period, mayimprove the cleanliness of the pool. A subset of the set (that subsetmay include one or more pool cleaning robots) may clean the pool when aremaining pool cleaning robot are unavailable. The subset may clean thepool in a slower manner and/or less efficient manner than the entireset—but this is not necessarily so.

The set may include pool cleaning robots that are equal, even identical,to each other and/or may include pool cleaning robots that differ fromeach other. The difference may include different hardware componentsand/or different software, code, firmware or malware configurations.

This application may refer to a first pool cleaning robot, a second poolcleaning robot, a third pool cleaning robot and a fourth pool cleaningrobot. The phrases first, second, third and fourth are merely used todifferentiate between the pool cleaning robots.

The set may include a first pool cleaning robot and a second poolcleaning robot that differ from each other. The difference may be, forexample, a difference between at least one unit out of a propulsion unitand a cleaning unit.

When such a set is provided at least one of the following conditions isfulfilled:

-   -   a. At least one pool cleaning robot of the set may be configured        to clean a sidewall of the pool.    -   b. At least one pool cleaning robot of the set may be configured        to perform collision avoidance steps for preventing a collision        between the first pool cleaning robot and the second pool        cleaning robot.    -   c. At least one pool cleaning robot of the set may be configured        to perform cable entanglement avoidance steps for preventing an        entanglement of a cable connected to the first pool cleaning        robot with a cable connected to the second pool cleaning robot.    -   d. Only one of the first pool cleaning robot and the second pool        cleaning robot may include a jet propulsion unit.    -   e. The cleaning unit of the first pool cleaning robot may        include a PVC brush wheel and does not include a Polyvinyl        acetate (PVA) sponge brush wheel; and a cleaning unit of the        second pool cleaning robot may include a PVA sponge brush wheel        and does not include a PVC brush wheel.    -   f. Only one of the first pool cleaning robot and the second pool        cleaning robot may include a sponge brush wheel.    -   g. Only one of the first pool cleaning robot and the second pool        cleaning robot may include a brush wheel that may include a        sponge brush wheel portion and a PVC brush wheel portion.    -   h. The first pool cleaning robot may be configured to remove        coarser dirt than the second pool cleaning robot.    -   i. The first pool cleaning robot may be configured to hover        between a bottom of a pool floor and a waterline.    -   j. The first pool cleaning robot may be configured to skim the        water surface and then sink to the bottom floor.    -   k. The first pool cleaning robot and the second pool cleaning        robot may be configured to clean different regions of the pool.    -   l. The first pool cleaning robot may include a detachable        module, the first pool cleaning robot and the second pool        cleaning robot may be configured to interchangeably receive the        detachable module.    -   m. The first pool cleaning robot may include a detachable        sensor, the first pool cleaning robot and the second pool        cleaning robot may be configured to interchangeably receive the        detachable sensor.    -   n. The first pool cleaning robot and the second pool cleaning        robot may be configured to clean a same region of the pool at        different manners.    -   o. The first pool cleaning robot and the second pool cleaning        robot may be configured to clean different regions of the pool.    -   p. The first pool cleaning robot operates as a master pool        cleaning robot during a certain period of time and the second        pool cleaning robot operates as a slave pool cleaning robot        during the certain period of time.    -   q. The first pool cleaning robot and the second pool cleaning        robot cooperatively reallocate cleaning tasks according to        failure to complete cleaning tasks.    -   r. The failure to completing tasks may be failure to traverse        slippery pool surfaces.    -   s. Only the first pool cleaning robot may be configured to clean        a slippery sloped bottom region of the pool.    -   t. The first pool cleaning robot may be configured to clean a        slippery flat bottom region of the pool.

Each one of the first pool cleaning robot and the second pool cleaningrobot may include a filtering unit for filtering fluid, a housing thatmay enclose various components such as the filtering unit, and acontroller for controlling the operation of the pool cleaning robot.

At least one pool cleaning robot of the set may be configured to clean asidewall of the pool. The pool cleaning robot may include cleaning unitcomponents (such as dedicated brushes) and/or propulsion unit components(such as water jet propulsion units).

At least one pool cleaning robot of the set may be configured to performcollision avoidance steps for preventing a collision between the firstpool cleaning robot and the second pool cleaning robot.

Various collision avoidance steps are listed in the text below.

A collision avoidance step may include maintaining different poolcleaning robots at different regions of the pool, keeping at least apredefined distance between different pool cleaning robots, sensing thelocation of other pool cleaning robots, notifying the other poolcleaning robots when there is a possibility of collision, and the like.

At least one pool cleaning robot of the set may be configured to performcable entanglement avoidance steps for preventing an entanglement of acable connected to the first pool cleaning robot with a cable connectedto the second pool cleaning robot.

At least one pool cleaning robot may sense the locations of its cableand a cable of another pool cleaning robot and may alert the other poolcleaning robot that the cables will be entangled if the other poolcleaning robot will continue its movement, may move itself in a mannerthat will prevent the cable entanglements, may be fed by informationfrom another device (within or outside the water of the pool) that thecables may become entangled and change its position, its course and thelike.

When the pool cleaning robots are allocated with different regions ofthe pool to clean—the allocation may take into account cableentanglements. The allocation can be dictated to the set, may be amendedby one or more pool cleaning robot of the set, and/or may be determinedby the set.

One or more pool cleaning robots may determine the allocation, may amenda previously provided (or preprogrammed) allocation, and the like. Poolcleaning robots of the set may participate in the allocation process—forexample may negotiate the desired allocation.

The allocation may be dictated to the set—preprogrammed, downloadedduring a software update, communicated from another device, and thelike. The allocation may be generated by a computerized system such asmobile device that is controlled by a user or may be operated withoutuser intervention—or any other computerized system. The computerizedsystem may be included in an external docking system, an external powersupply and/or within a submerged docking system.

The allocation of regions may change over time and/or may be fixed.

The allocation of regions may be determined and/or updated and/orgenerated with regarded to (or regardless) to at least one of thefollowing:

-   -   a. One or more capabilities of the pool cleaning robots of the        set. These capabilities may include cleaning capabilities and/or        maneuvering capabilities and/or exit from the pool capabilities.        There may be some pool cleaning robots that cannot clean certain        regions of the pool and will not be allocated to clean these        regions. There may be pool cleaning robot that may be more        effective in cleaning slippery surfaces (for example have better        maneuverability and/or grip and/or cleaning elements that are        capable of cleaning slippery surfaces) and/or pool cleaning        robots that are faster than others. These pool cleaning robots        will be prioritized to clean these slippery surfaces.    -   b. The status of the pool cleaning robots of the set—for example        cleanliness of the filtering unit, energy resources status        (battery fullness), any fault or error, progress (or lack of        progress) of one or more cleaning tasks allocated to one or more        pool cleaning robots, deviations of pool cleaning robot from        allocated path, and the like. For example—a pool cleaning robot        that has a dirtier filtering unit may be allocated to clean        cleaner surfaces and/or smaller surfaces than a pool cleaning        robot of similar configuration that has a cleaner filtering        unit. Yet for another example—a pool cleaning robot that has an        emptier battery may be allocated with cleaning smaller regions        and/or regions that are easier to clean and/or require less        climbing and/or slipping than another pool cleaning robot that        has a fuller battery. Yet for a further example—the allocation        may allow emptying a battery of one or more cleaning robots        and/or the clogging of one of more filtering unit of a pool        cleaning robots and the like. A faulty pool cleaning robot may        be allocated smaller cleaning regions or any other regions that        may be cleaned despite the fault. For example—a faulty jet        propulsion unit that may prevent a pool cleaning robot from        hovering may result in allocating to that pool cleaning robot        regions that do not require hovering (such as stairs). A pool        cleaning robot that significantly deviates from its designed        cleaning path may be allocated to clean other regions of the        pool and/or regions of the pool that are easier to clean.    -   c. Location (and even existence) of power cable cords of pool        cleaning robots. The location may change over time and may be        tracked and/estimated to prevent cable entanglement.    -   d. Pool parameters such as materials of sidewalls, bottom of the        pool, structure of the pool—flat bottom surfaces, sloped bottom        surfaces, materials from which the pool is made, grip level        associated with the different surfaces of the pool, slope of        different surfaces of the pool, obstacles such as stairs,        ladder, drain, lighting elements and the like. The        maneuverability of the pool cleaning robot will be taken into        account during the allocation. For example—cleaning stairs may        require hovering in the water of the pool and thus cleaning        stairs will be allocated to a pool cleaning robot with hovering        capabilities. Yet for another example—a pool cleaning robot with        a sponge brush wheel may be allocated to clean sidewalls and/or        sloped surfaces and/or slippery surfaces.    -   e. Status of the pool—turbidity, aggregation of algae, submerged        dirt, and the like. A pool that is dirtier (or dirtier regions        of the pool) may require, at least as an initial phase, using        coarser cleaning—and allocating pool cleaning robots of coarser        cleaning capabilities to perform the cleaning of the dirtier        parts of the pool. Higher turbidity and/or a more slippery pool        may require keeping a greater distance between pool cleaning        robots—and or defining a larger distance between a border of a        region allocated to a pool cleaning robot and an aggregation of        algae, or other slippery elements of the pool.    -   f. Presence of people within the pool. The people may be        confined to a certain part of the pool and the allocation may        include preventing the pool cleaning robot from cleaning that        certain part of the pool. The cleaning process may be stopped        when one or more people enter the pool, or may continue cleaning        even when people are within the pool. The entrance of people to        the pool may be sensed by one or more pool cleaning robots of        the set (for example using an image sensor and image processing)        or by another system that may communicate the event to one or        more pool cleaning robots. The set may exit the pool when a        person enters the pool.    -   g. Timing parameters—allowed duration of cleaning process, time        of day, season. For example—shorter allowable time frames may        induce at least one pool cleaning robot to perform a faster        cleaning operation—even if the faster cleaning operation is less        effective. The traveling speed of at least one pool cleaning        robot may be increased to comply with smaller time frames. The        number of pool cleaning robot of the set that will participate        in the cleaning of the pool may change based on the time window.        Sometime windows may require using all the pool cleaning robot        of the set. Longer time windows may allow using only some of the        pool cleaning robots of the set.    -   h. Cleaning policy—for example limitations on the number of        exits from the pool during a cleaning session, limitation on the        duration of the overall cleaning process, a required cleanliness        of pool at the end of the cleaning process, allowing or        forbidding one of the pool cleaning robots of the set to be        stuck in the pool at the end of the cleaning process,        prioritizing the cleaning of some pool surfaces, and the like.        The prioritized pool surfaces may be cleaned more times and/or        in a more extensive manner than non-prioritized surfaces. The        priority may be dictated by a third party, may be determined by        one or more pool cleaning robot, and the like. The priority may        be responsive to success or failure in previous cleaning        attempts, to the current or past status of different regions of        the pool, and the like.

A cable entanglement avoidance step may include changing the progress ofone or more pool cleaning robot and/or allocating cleaning tasks toprevent such entanglement.

Different cables of different pool cleaning robots may be stretched fromdifferent external units (such as power supply units) located outsidethe pool. The locations of these units may be fed to one or more poolcleaning robot of the set and/or to another computerized system. Thecable entanglement avoidance steps may take into accounts theselocations.

For example—the cable entanglement avoidance steps may includeallocating the cleaning zones to reduce the chances of cableentanglements.

The allocation of regions for reducing the chances of cable entanglementmay include:

-   -   a. Receiving or calculating an expected cleaning region of a        certain pool cleaning robot.    -   b. Based on the expected cleaning region, calculating the        possible locations of the cable connected between an external        unit and the certain pool cleaning robot.    -   c. Trying to prevent the cable from crossing an expected        cleaning region of another pool cleaning robot.

The allocation of regions for reducing the chances of cable entanglementmay include:

-   -   a. Receiving or calculating expected cleaning region of        different pool cleaning robots.    -   b. Receiving or calculating information about the cleaning paths        of the different pool cleaning robots—especially mappings        between locations and timings of the different pool cleaning        robots during the cleaning process.    -   c. Based on the expected cleaning regions and the mapping,        calculating the possible locations (and timing associated with        these locations) of different cables connected between one or        more external units and the different pool cleaning robot.    -   d. Checking, based on the locations and timings of the different        cables, whether one or more cables will be entangled- and if so        either changing the allocated regions and/or changing at least        one cleaning path of at least one pool cleaning robot (changing        the shape, size and/or timing) to prevent said crossing.

The checking and/or the changing (of step d above) may be executed in aniterative manner, in a non-iterative manner, by one or more poolcleaning robot, by a master pool cleaning robot, by a slave poolcleaning robot, in a distributed manner, in a non-distributed manner, byan external computerized system (external to the pool), and the like.

For example—one or more pool cleaning robots may receive the informationfrom steps a, b, and c, and may perform the checking of step d.

Distributed manner indicates that a pool cleaning robot and at least oneother pool cleaning robot (or another computerized entity) participatesin the process.

If the one or more pool cleaning robot finds a possible collision it mayupdate the cleaning paths to prevent the cable entanglement.

If the one or more pool cleaning robot finds a possible collision thenthey may inform at least one of the involved pool cleaning robots (poolcleaning robots that are involved in the potential cable entanglement)about the possible collision.

One or more of the involved pool cleaning robots may re-calculate theircleaning path and communicate the at least one updated cleaning path tothe one or more pool cleaning robots.

The one or more pool cleaning robots may evaluate whether this amendmentsolved the potential cable entanglement.

The cable entanglement avoidance steps may include, in addition to orinstead of the steps mentioned above, determining cable entanglementreduction measures that may include sensing a cable entanglement event,sensing a potential cable entanglement event, responding to the sensing.

The cable entanglement avoidance steps may include, in addition to orinstead of the steps mentioned above, resolving a cable entanglementevent after the cables were entangled. This may include introducing amovement between entangles pool cleaning robot (pool cleaning robotsthat have their cables entangled).

The sensing (of the cable entanglement event and/or of the potentialcable entanglement event) may be performed using images sensors,proximity sensors that may sense that two or more cables are tooproximate to each, that may sense that the pool cleaning robots are tooclose to each other, that pool cleaning robots are cross each otherpaths in a manner that will result in a cable entanglement. The sensorsmay be included in one or more pool cleaning robot, and/or outside thepool cleaning robots.

The sensing may involve monitoring the movement of the pool cleaningrobots and sensing when their cable may be entangled. This may involvespeed sensing and/or acceleration sensing and/or direction sensing, andthe like.

The sensing may involve sensing forces applied on the pool cleaningrobots and/or deviations from expected propagation of the pool cleaningrobot due to cable entanglement. The sensing may include accelerometers,motion sensors, image sensors and the like.

The responding to the sensing may include stopping the progress of oneor more pool cleaning robot until another pool cleaning robot willchange its position and avoid the cable entanglement. The pool cleaningrobot that stops may be requested or instructed to stop for a certainperiod and/or may determine the predefined period by itself.

The responding to the sensing may include changing the progress of oneor more pool cleaning robot. For example, changing the speed and/ordirection of movement.

The change of speed and/or movement may be dictated to the pool cleaningrobot and/or may be determined by the pool cleaning robot.

The change of direction may include reversing the direction or changingthe direction by ninety to two hundred and seventy degrees, propagatingto a direction that will increase the distance between the pool cleaningrobots, propagating in a direction that will increase the distancebetween the pool cleaning robots and the cleaning region allocated tothe other pool cleaning robot.

Any step or measure mentioned in relation to the cable entanglementavoidance steps may be applied mutatis mutandis to pool cleaning robotcollision avoidance.

Only one (or both) of the first pool cleaning robot and the second poolcleaning robot may include a jet propulsion unit. A jet propulsion unitmay enable cleaning slippery flat surfaces, slippery wall climbing,slippery slopes cleaning, waterline cleaning, overcoming obstacles andsidewall sideways cleaning.

The term “jet” refers to a jet of fluid.

The cleaning unit and/or the propulsion unit of the pool cleaning robotsof the set may be determined based on the characters of the pool. Theshape, size and materials of the pool sidewalls and bottom may determinethe profiling of which pool cleaning robots should populate the set thatshould clean the pool or a certain region.

Pools with a flat bottom are easier to clean than pools that have one ormore sloped bottom surfaces—especially steep sloped bottom surfaces.Pools that include sloped bottom surfaces may or may not include ahopper (deepest part of the pool) that interfaces with one or moresloped bottom surfaces. There are pools that include hoppers ofsignificant size of of insignificant size. Controlled movement alongsloped bottom surfaces—and especially steep sloped bottom surfaces maybe challenging—especially when the sloped bottom surfaces are slippery.

It should be noted that the grip level of any surface of a pool may bedetermined by the material of that surface (ceramics, marble, paintedand certain PVC or GRP may be more slippery than concrete painted ornot), the slope of the surface and the cleanliness of thatsurface—especially whether algae or other or slippery dirt is aggregatedon that surface.

Moving and/or cleaning sidewalls as well as moving and/or cleaningsloped bottom surfaces and slippery flat surfaces may be eased (and evenfacilitated) by having dedicated brush wheels such as a sponge brushwheel—especially a Polyvinyl acetate (PVA) sponge brush wheel (such asthe synthetic chamois by Kanebo co. Ltd in Japan) and/or with a hybridbrush that includes a sponge brush portion and a non-sponge brushportion. For example—a hybrid brush that may include a PVC portion and aPVA sponge portion.

Sponge brush wheels are more expensive—and only a part of the poolcleaning robots of the set may have sponge brush wheels.

The set may include a pool cleaning robot that is configured to performsidewall cleaning and another pool cleaning robot that is not configuredto perform sidewall cleaning.

Different brushes have different costs and using a set that includespool cleaning robot that have different brushes may reduce the cost ofthe set.

Different pool cleaning robots of the set may be configured to removedifferent types of dirt—one pool cleaning robot may be configured toremove coarser dirt than the second pool cleaning robot.

The set may include a pool cleaning robot that may be configured tohover between a bottom of a pool floor and a waterline performing as ahovering submarine pool cleaner—while another pool cleaning robot of theset may or may not have this capability.

The set may include a pool cleaning robot that may be configured to skimthe water surface and then sink to the bottom floor—while another poolcleaning robot of the set may or may not have this capability.

One of pool cleaning robots of the set may include a detachable modulethat may be interchangeably exchanged between the pool cleaning robotsof the set.

The detachable module may be a battery, a filtering unit, a sensor, acontroller, and the like.

Exchanging the detachable module may reduce cost (by sharing thedetachable module between the pool cleaning robots),

One detachable module (that may be detached to different pool cleaningrobot at different points in time) may increase the redundancy of theset, enables to perform a flexible resource management, and the like.

The exchange may occur for different reasons—for example a malfunctionin one of the pool cleaning robots, a shortage of power supply, aclogged filter, a task that requires the detachable module, and thelike.

During such an exchange, a detachable module is removed from a firstpool cleaning robot and received by a second pool cleaning robot. Theexchange may require human intervention or may be executed without humanintervention.

The detachable module may be detachably connected to the housing of thepool cleaning robot or to any other part of the pool cleaning robot byany mechanical and/or magnetic and/or electrostatic manner—such as by alocking and unlocking mechanism.

The set may include pool cleaning robots that may be allocated to cleandifferent regions of the pool, the same region of the pool and the like.The different regions of the pool may not overlap or may partiallyoverlap.

A partial overlap may be required, for example, to prevent gaps in thecoverage of the set.

The different regions may be of the same type or different types.Regions of different types may include sidewall regions, flat bottomregions, sloped bottom regions, and the like.

Different regions may have the same size and/or the same shape and/ordifferent sizes and/or different shapes.

One or more regions may be allocated to a pool cleaning robot. A regionmay include any part of the pool—one or more sidewalls of the pool, oneor more parts of one or more sidewalls of the pool, one or more bottomsurface of the pool, one or more parts of one or more bottom surface ofthe pool, one or more stairways of the pool, one or more parts of one ormore stairways of the pool, one or more part of the waterline of thepool, one or more external surface of the pool, one or more parts of oneor more external surface of the pool, one or more peripheral region ofthe pool that may be submerged and/or not submerged, and any combinationthereof.

When a set of pool cleaning robots (the set include first and secondpool cleaning robots) includes pool cleaning robots such as the firstand the second pool cleaning robots—that are allocated to clean the sameregions of the pool, at least one of the following conditions may befulfilled:

-   -   a. The first pool cleaning robot and the second pool cleaning        robot may be configured to clean a same region of the pool at        different manners.    -   b. The first pool cleaning robot and the second pool cleaning        robot may be configured to clean a same region of the pool at        the same manners.    -   c. The first pool cleaning robot may be configured to perform a        preliminary cleaning of the region and the second pool cleaning        robot may be configured to perform a supplementary cleaning of        the region.        -   i. The preliminary cleaning may be faster than the            supplementary cleaning.        -   ii. The preliminary cleaning may be slower than the            supplementary cleaning.        -   iii. The preliminary cleaning may be coarser than the            supplementary cleaning.    -   d. The second pool cleaning robot may be configured to follow        the first pool cleaning robot.    -   e. The second pool cleaning robot may be configured to perform        the supplementary cleaning of the region while staying within a        cloud of debris elevated during the preliminary cleaning of the        region.

At least one pool cleaning robot of the set may act as master poolcleaning robot—it may control at least one slave pool cleaning robot ofthe set. A single master pool cleaning robot may control one or moreother pool cleaning robots. A single slave pool cleaning robot may becontrolled by one or more master pool cleaning robots.

The roles of the pool cleaning robots may be fixed or may be changedover time.

When the roles change over time a slave pool cleaning robot may become amaster pool cleaning robot. The change of roles may occur when themaster pool cleaning robot malfunctions—or for any other reason.

A pool cleaning robot may be a master pool cleaning robot in relation tocertain operations- and may be a slave pool cleaning robot in relationto other operations—either at the same time and/or at different times.

There may be provided multiple control layers so that a pool cleaningrobot may be a slave of another pool cleaning robot and at the same timebe a master of a further pool cleaning robot. For example, a third poolcleaning robot may control a second pool cleaning robot, and the secondpool cleaning robot may control a first pool cleaning robot. Yet foranother example—the second pool cleaning robot may be controlled by eachone of the first and third pool cleaning robots.

Assuming that the set includes at least a master pool cleaning robot anda slave pool cleaning robot then at least one of the followingconditions is fulfilled:

-   -   a. The master pool cleaning robot and the slave pool cleaning        robot may be configured to clean different regions of the pool.    -   b. The master pool cleaning robot and the slave pool cleaning        robot may be configured to a clean same region of the pool.    -   c. At least one of the slave pool cleaning robot and the master        pool cleaning robot may be configured to apply collision        avoidance maneuvers to prevent collisions between the slave and        master pool cleaning robots.    -   d. The master pool cleaning robot may be configured to control        at least one cleaning related operation of the slave pool        cleaning robot.    -   e. The master pool cleaning robot may be configured to instruct        the slave pool cleaning robot to perform cleaning operations        within a predefined region of the pool, and wherein the slave        pool cleaning robot may be configured to perform the cleaning        operations only within the predefined region of the pool.    -   f. The master pool cleaning robot may be configured to apply        collision avoidance maneuvers to prevent collisions between the        master pool cleaning robot and the slave pool cleaning robot.    -   g. The master pool cleaning robot may be configured to instruct        the slave pool cleaning robot to apply collision avoidance        maneuvers to prevent collisions between the master pool cleaning        robot and the slave pool cleaning robot.    -   h. The master pool cleaning robot has cleaning elements that        equal to cleaning elements of the slave pool cleaning robot.    -   i. The master pool cleaning robot has cleaning elements that        differ from cleaning elements of the slave pool cleaning robot.    -   j. The master pool cleaning robot has coarser cleaning elements        than the slave pool cleaning robot.    -   k. The master pool cleaning robot has finer cleaning elements        than the slave pool cleaning robot.    -   l. Only one of the master pool cleaning robot and the slave pool        cleaning robot may be configured to climb on a sidewall of the        pool and clean the sidewall of the pool and/or its waterline.    -   m. Only one of the master pool cleaning robot and the slave pool        cleaning robot may be configured to travel slippery surfaces of        a pool.    -   n. Both master pool cleaning robot and the slave pool cleaning        robot may be configured to travel slippery surfaces of a pool.    -   o. Only one of the master pool cleaning robot and the slave pool        cleaning robot may include a jet propulsion unit.    -   p. Both the master pool cleaning robot and the slave pool        cleaning robot may include a jet propulsion unit.    -   q. The master pool cleaning robot may include a jet propulsion        unit that differs from a jet propulsion unit of the slave pool        cleaning robot.    -   r. At least one pool cleaning robot of the set may be configured        to generate information about a status of a pool, and wherein        the master pool cleaning robot may be configured to allocate a        cleaning task to the slave pool cleaning robot based on the        information about the status of the pool. The status of the pool        may include cleanliness of the pool.    -   s. The allocating of the cleaning task may include determining a        region of the pool to be cleaned by the slave pool cleaning        robot.    -   t. The allocating of the cleaning task may include determining a        manner of cleaning of a pool region of the pool to be cleaned by        the slave pool cleaning robot.    -   u. The master pool cleaning robot may be configured to receive        instructions from another device regarding an association        between different pool cleaning robots of the sets and the        different regions of the pool.    -   v. The master pool cleaning robot may be configured to receive        instructions from another device regarding an association        between different pool cleaning robots of the set and the        different regions of the pool, and to amend the association        based on the status of the pool.    -   w. The master pool cleaning robot may be configured to allocate        a cleaning task to the slave pool cleaning robot based on a        status of the slave pool cleaning robot and a status of the        master pool cleaning robot.    -   x. The master pool cleaning robot may be configured to allocate        a cleaning task to the slave pool cleaning robot based on a        status of the slave pool cleaning robot.    -   y. The master pool cleaning robot may be configured to receive a        definition of the different regions of the pool and to define        overlap areas of the pool that may be cleaned, at different        points in time, by more than a single pool cleaning robot.    -   z. The master pool cleaning robot may be configured to        communicate information about the overlap areas to the slave        pool cleaning robot.    -   aa. The master pool cleaning robot may be configured to track a        position of the slave pool cleaning robot.    -   bb. Each pool cleaning robot of the set may be configured to        track a position of at least one other pool cleaning robot of        the set    -   cc. The master pool cleaning robot and the slave pool cleaning        robot may be configured to replace roles.    -   dd. The master pool cleaning robot may be configured to receive        information about a location of a cord that may be connected to        the slave pool cleaning robot and to allocate a region to be        cleaned by the slave pool cleaning robot based on the        information about the location of the cord that may be connected        to the slave pool cleaning robot and based on estimated or        actual location of another cord that may be connected to the        master pool cleaning robot.    -   ee. The master pool cleaning robot may be configured to sense a        location of a cord that may be connected to the slave pool        cleaning robot and to allocate a region to be cleaned by the        slave pool cleaning robot based on the sensed location of the        cord that may be connected to the slave pool cleaning robot and        based on estimated or actual location of another cord that may        be connected to the master pool cleaning robot.    -   ff. The master pool cleaning robot may include at least one        sensor that may be not included in the slave pool cleaning        robot.    -   gg. The master pool cleaning robot may include an image sensor        that may be not included in the slave pool cleaning robot.

The master pool cleaning robot may include an image sensor that may be adetachable modular sensor to be reattached to a slave pool cleaningrobot.

A cleaning process executed by a certain pool cleaning robot may bemonitored by the certain pool cleaning robot. Additionally oralternatively, one or more pool cleaning robots of the set may beconfigured to monitor the cleaning process executed by the certain poolcleaning robot.

The monitoring of the cleaning process may include imaging a region (ora part of the region) that is cleaned by the pool cleaning robot,evaluating a turbidity or lighting quality (by an image sensor or anyother sensor) of the fluid near the region (or a part of the region)that is cleaned by the pool cleaning robot, measuring the grip level ofthe region (or a part of the region) that is cleaned by the poolcleaning robot, measuring the outcome of the cleaning process (whetherthe entire region was cleaned, are there any cleaning gaps, what is thecleanliness level of different locations within the region, the durationof the cleaning process, energy consumed during the cleaning process,and the like.

An automatic co-operative allocation and reallocation of cleaning taskswithin the set may be based on the outputs of the monitoring as comparedto pre-set failure or success rates to complete tasks that may bemeasured by ongoing trial and error during a single cleaning cycle.These are based on preset normal conditions that are a function of thepropulsion abilities and the cleaning abilities in ideal poolconditions.

For example—a pool cleaning robot that successfully cleaned a certainregion may be re allocated to a larger region and/or a tougher region toclean in a cleaning cycle.

Yet for another example—a pool cleaning robot that cleaned its region ata faster rate than another pool cleaning robot may be allocated a largerregion than the other pool cleaning robot.

Fast rate or slow rate may be a function of the success or failure tomatch nominal expected propagation movements by the pool cleaning robot.

For example, an odometer or acceleration device that measures a failureof the pool cleaning robot to move despite movement of the wheel(s) ortrack(s) may mean that this specific pool cleaning robot may need to bereallocated to another task. The same rules apply to tasks such ascleaning walls, waterlines, slopes and the like.

The determination may be responsive to the state of the region beforeand after the cleaning process, to the type of the region (sidewall,bottom surface—sloped of flat), to the energy consumption associatedwith the cleaning process (energy consumption may be reported by thepool cleaning robot—for example by monitoring the level of its battery),ability to overcome slippery surfaces on vertical walls, slopes orwithout idling on flat surfaces and the like.

A movement of a certain pool cleaning robot may be monitored by thecertain pool cleaning robot. Additionally, or alternatively, one or morepool cleaning robots may be configured to monitor the movement of thecertain pool cleaning robot. The movement may be a part of a cleaningprocess and/or may follow (or precede) the cleaning process.

One or more pool cleaning robots of the set may help one or more otherpool cleaning robots of the set. The one or more pool cleaning robot ofthe set may request the help. Additionally or alternatively, anotherpool cleaning robot of the set may detect that the one or more poolcleaning robot needs help.

A first pool cleaning robot may help a second pool cleaning robot byperforming, for example, at least one out of:

-   -   a. Pushing the second pool cleaning robot.    -   b. Pulling the second pool cleaning robot, otherwise affecting a        movement of the second pool cleaning robot.    -   c. Providing a module (for example—filter, battery, sensor) to        the second pool cleaning robot.    -   d. Taking a detachable module (for example—filter, battery,        sensor) from the second pool cleaning robot.    -   e. Cleaning a region allocated to the second pool cleaning robot        (“second region”).    -   f. Shredding and/or collecting debris or dirt that may reside in        the second region.    -   g. Shredding and/or collecting debris that may be positioned in        a portion of the pool that leads to the second region.    -   h. Assisting the second pool cleaning robot to climb sloped        and/or slippery surfaces of the pool.    -   i. Performing a cleaning process of the second region before the        first pool cleaning robot starts cleaning the second region,        after the first pool cleaning robots ends the cleaning of the        second region or at any other time.    -   j. Sensing a state of the second region.    -   k. Sensing a state of the second pool cleaning robot.    -   l. Transmitting or receiving control information and/or sensed        data to or from the second pool cleaning robot.

At least one of the pool cleaning robot of the set may have anultrasonic wave generator for removing particles. A non-limiting exampleof such a pool cleaning robot is provided in U.S. Pat. RE45852 which isincorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of: (i) a ballast tank for controlling a buoyancy of thesubmarine pool cleaner, (ii) at least one cleaning element for cleaningdebris from an underwater surface of a pool while the pool cleaningrobot hovers over the underwater surface, (iii) a propulsion module(unit) that is configured to propel the submersible pool cleaner and asteering module that includes a rudder and diving planes. A non-limitingexample of such a pool cleaning robot is illustrated in FIG. 6A (denoted400) and in US patent application publication number 2016/0060887, whichis incorporated herein by reference. Yet another pool cleaning robot ofthe set may differ from such a type of pool cleaning robot.

At least one of the pool cleaning robots of the set may include at leastone out of (i) a side brush located at the side of the housing of thepool cleaning robot, (ii) an upper brush that is located (at least atcertain points of time) above the housing, (iii) a bottom brush locatedbeneath the housing, (iv) one or more arms that are coupled to one ormore cleaning brushes, any arm may extend outside the housing, mayinclude one or more joints, may be static or movable. Non-limitingexamples of arms and brushes are illustrated in FIGS. 5 and 6A and in USpatent application publication number 2016/0060887, which isincorporated herein by reference.

At least one of the pool cleaning robots of the set may include apropulsion unit that may include one or multiples jet generators. Forexample—the propulsion unit may include first jet generator that isconfigured to generate first fluid jets while the pool cleaning robotpropagates towards the underwater surface; a second jet generator of thepropulsion unit may be configured to generate second fluid jets whilethe pool cleaning robot hovers over an underwater surface. The firstfluid jets may be may not be stronger than the second fluid jets.Non-limiting examples of jet propulsion units are illustrated in FIGS. 5and 6A and in US patent application publication number 2016/0060887,which is incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of a transmission coupled between a brushing element and a drivemotor, the transmission is arranged to convert a rotary movement inducedby the drive motor to a combination of (a) a rotary movement of thebrushing element about a brushing element axis, and (b) a reciprocalmovement of the brushing element in parallel to the brushing elementaxis. A non-limiting example of such a pool cleaning robot isillustrated in either one of U.S. Pat. Nos. 9,145,699, 9,410,338 and9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of (i) multiple movable elements that are coupled to thehousing, each movable element is arranged to induce a movement of thehousing when the movable element is in contact with a surface of thepool; and (ii) an imbalance induction unit that is arranged to introducean imbalance between at least two movable elements, the imbalanceresults in a change in a direction of propagation of the cleaning robot;wherein the imbalance induction unit is arranged to induce the imbalanceas a result of at least one out of (a) a movement of a nozzle that isarranged to output fluid from the cleaning robot, and (b) a movement ofa diaphragm that is coupled to the housing.

At least one of the pool cleaning robots of the set may include at leastone out of a housing that includes a right opening, a left opening and acenter opening; wherein the right opening is preceded by a right fluidconduit that is arranged to direct fluid to the right of the housing,the left opening is preceded by a left fluid conduit that is arranged todirect the fluid towards the left of the housing; and the centralopening is preceded by a central conduit; a nozzle manipulator that iscoupled to the nozzle and arranged to rotate the nozzle about an nozzleaxis such as to alter an orientation of the nozzle in relation to animaginary longitudinal axis of the housing; a fluid interfacing unitarranged to direct fluid from the nozzle (a) towards the central fluidconduit when the nozzle is at a first orientation, (b) towards the rightfluid conduit when the nozzle is at a second orientation, and (c)towards the left fluid conduit when the nozzle is at a thirdorientation; wherein the first orientation differs from the second andthird orientations.

At least one of the pool cleaning robots of the set may include at leastone out of a pump motor, a drive motor and an impeller that aresubstantially closer to a front edge of the housing than to a rear edgeof the housing. A non-limiting example of such a pool cleaning robot isillustrated in either one of U.S. Pat. Nos. 9,145,699, 9,410,338 and9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of an optical sensor that includes at least one light sourcethat illuminates an area of a surface of the pool being cleaned by thecleaning robot through optical lens at a non-vertical angle, a detectorable to generate, based upon light from the area of the surface of thepool, detection signals indicative of a motion of the cleaning robot;and a processor arranged to receive the detection signals and todetermine a motion characteristic or a location characteristic of thecleaning robot. A non-limiting example of such a pool cleaning robot isillustrated in either one of U.S. Pat. Nos. 9,145,699, 9,410,338 and9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of a first compass arranged to generate first directionalinformation; a second compass arranged to generate second directionalinformation; wherein the first and second compasses are spaced apartfrom each other; and a processor; arranged to receive directionalinformation from the first and second compasses and to determine atleast one of a location parameter and a directional parameter of thecleaning robot based upon at least the first and second directionalinformation.

At least one of the pool cleaning robots of the set may include afiltering unit includes a first filter that has a first filtering leveland a second filter that has a second filtering level that differs fromthe first filtering level. A non-limiting example of such a poolcleaning robot is illustrated in either one of U.S. Pat. Nos. 9,145,699,9,410,338 and 9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of a housing having a front portion, a rear portion, a door anda hinge; wherein the door is pivotally connected to the rear portion ofthe housing via the hinge; wherein the rear portion includes a rearopening; wherein the door is arranged to move between a closed positionin which the door substantially closes the rear opening and an openposition in which the door does not close the rear opening; wherein thedoor includes a floating element or is coupled to a floating element,wherein the floating element is positioned and shaped to induce the doorto move to the closed position when the cleaning robot is submerged influid and to remain in an open position when out of water in ahorizontal position. A non-limiting example of such a pool cleaningrobot is illustrated in either one of U.S. Pat. Nos. 9,145,699,9,410,338 and 9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of a housing that include a front portion and a rear portion,and further includes a door and a hinge. Wherein the door is pivotallyconnected to the rear portion via the hinge; wherein the rear portionincludes a rear opening; wherein the door is arranged to move between aclosed position in which the door substantially closes the rear openingand an open position in which the door does not close the rear opening;wherein the door includes a floating element or is coupled to a floatingelement, wherein the floating element is positioned and shaped to inducethe door to move to the closed position when the cleaning robot issubmerged in fluid. A non-limiting example of such a pool cleaning robotis illustrated in either one of U.S. Pat. Nos. 9,145,699, 9,410,338 and9,222,275, all being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include one ormore brush wheels (auxiliary brush wheels) that may be positioned at thecenter of the bottom of the pool cleaning robot or be positioned suchthat the one or more brush wheels does not extend beyond the sides ofthe bottom of the pool cleaning robot. Thus—a top view of the poolcleaning robot would not reveal the bottom brush wheel. A non-limitingexample of such a pool cleaning robot is illustrated in either one ofU.S. Pat. Nos. 8,424,142, 9,021,645 and 9,021,645, all beingincorporated herein by reference.

At least one of the pool cleaning robots of the set may include at leastone out of (i) interfacing modules (such as wheels and/or tracks)arranged to interface between the pool cleaning robot and theenvironment, and (ii) an interface manipulator that is arranged tochange a spatial relationship between (a) the housing and (b) a selectedinterfacing module of the group, during an exit process during which thepool cleaning robot exits the pool. A non-limiting example of such apool cleaning robot is illustrated in US patents application publicationnumber 2015/0101135 that is being incorporated herein by reference.

At least one of the pool cleaning robots of the set may include aninterface for coupling an extraction element to the pool cleaning robot,during a pool exit process; and wherein during at least a part of thepool exit process an upper end of the interface may be higher than thehousing. A non-limiting example of such a pool cleaning robot isillustrated in US patents application publication number 2017/0057760that is being incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) a propulsion unit such as a drive system that is configured tomove the pool cleaning robot, during a pool exit process, at a path thatleads outside the pool, (ii) a pump motor that is configured to rotatean impeller during at least a part of the pool exit process for forcingwater to exit the pool cleaning robot. A non-limiting example of such apool cleaning robot is illustrated in US patents application publicationnumber 2017/0057759 that is being incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) a sensor for sensing a cleanliness of a filtering unit whilesubmerged in water, (ii) a controller that is configured to determine,based on the cleanliness of the filtering unit, a cleaning process to beapplied on the pool cleaning robot by an external system; and (iii) acommunication unit that is configured to transmit information about thecleaning process. A non-limiting example of such a pool cleaning robotis illustrated in US patents application publication number 2017/0037648that is being incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) a filtering unit for filtering water that passes through the poolcleaning robot; (ii) a sensor for sensing a cleanliness of the filteringunit (a) before the pool cleaning robot reaches an external system thatis configured to apply a cleaning process on the pool cleaning robot and(b) at one or more points in time during the cleaning process; and (iii)a communication unit that is configured to transmit information aboutthe cleanliness of the filtering unit. A non-limiting example of such apool cleaning robot is illustrated in US patents application publicationnumber 2017/0037648 that is being incorporated herein by reference.

At least one pool cleaning robot of the set may include a cleaning brush(brush wheel) that may include a central portion that has a longitudinalaxis; a right-handed fin that surrounds a first section of the centralportion; a left-handed fin that surrounds a second section of thecentral portion; first protuberances that are oriented in relation tothe right-handed fin; and second protuberances that are oriented inrelation to the left-handed fin. A non-limiting example of such acleaning brush is illustrated in US patents application publicationnumber 2014/0366297 that is being incorporated herein by reference.

At least one pool cleaning robot of the set may include a cleaning brush(brush wheel) that may include a central portion that has a longitudinalaxis; first fins that have a positive slope in relation to thelongitudinal axis and surround a first section of the central portion;second fins that have a negative slope in relation to the longitudinalaxis and surround a second section of the central portion; firstprotuberances that are oriented in relation to the first fins; andsecond protuberances that are oriented in relation to the second fins. Anon-limiting example of such a cleaning brush is illustrated in USpatent application publication number 2014/0366297 that is beingincorporated herein by reference.

At least one pool cleaning robot of the set may include a filtermanipulator that is at least partially located within the housing and isarranged to (a) receive a filter and (b) introduce a movement betweenthe filter and the housing thereby positioning the filter within afiltering position in which the filter is at least partially disposedwithin a fluid path formed between a first fluid opening and a secondfluid opening of the housing thereby allowing the filter to apply afiltering operation on fluid that passes through the fluid path. Thefilter manipulator may be arranged to receive the filter and at leastone additional filter and to position the filter at the filteringposition. The filter manipulator may include (i) a filter storage modulethat includes multiple compartments for receiving multiple filtersincluding the filter, and (ii) a movement mechanism that is arranged tointroduce the movement between the filter and the housing by moving thestorage module. The movement may include extracting the filter from thehousing, receiving the filter to the housing, positioning the filter ata filtering position or at another position within the housing, and thelike. A non-limiting example of such a pool cleaning robot isillustrated in US patents application publication number 2015/0292222that is being incorporated herein by reference.

At least one pool cleaning robot of the set may be controlled in aninteractive or non-interactive manner by another device (such as but notlimited to a mobile computer).

At least one pool cleaning robot of the set may include at least one ofa receiver and a controller. The receiver may be a part of acommunication module. The receiver may be configured to receivedemarcation information that defines pool zones and pool cleaning robotoperational parameters related to the pool zones. The demarcationinformation may be generated by a mobile computer and under a control ofa user. The controller may be configured to control a cleaning operationof the pool cleaning robot, based on the demarcation information. Thecleaning operation may include passing the non-filtered fluid through afiltering unit to provide the filtered fluid while moving the poolcleaning robot by the propagation system. A non-limiting example of sucha pool cleaning robot is illustrated in US patents applicationpublication number 2017/0212523 that is being incorporated herein byreference.

At least one pool cleaning robot of the set may include at least one ofa receiver and a controller. The receiver may be a part of acommunication module. The communication module is configured to receiveend of cycle location information that defines an end of cycle location;wherein the end of cycle location information is generated by a mobilecomputer and under a control of a user. The controller is configured tocontrol multiple cleaning cycles of the pool cleaner; wherein aperforming of the multiple cleaning cycles comprises positioning thepool cleaner, at an end of each cleaning cycle of the multiple cleaningcycles, at the end of cycle location; wherein each cleaning cyclecomprises passing the non-filtered fluid through the filtering unit toprovide the filtered fluid while moving the pool cleaner by thepropagation system. A non-limiting example of such a pool cleaning robotis illustrated in U.S. patent application Ser. No. 15/463,161 that isbeing incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) one or more sensors for sensing an actual yaw of the pool cleanerand an actual orientation of the pool cleaner (ii) a propulsion unitthat may be configured to move the pool cleaner along a cleaning path,during a cleaning process of a certain region of a sidewall of the pool;wherein the cleaning path comprises a cleaning path segment that has acleaning path segment yaw that is a non-vertical yaw; wherein thecertain region is fully submerged; and (iii) a controller that isconfigured to control the at least one steering element, based on theactual yaw of the pool cleaner. The cleaning path segment may or may notbe horizontal. A non-limiting example of such a pool cleaning robot isillustrated in FIGS. 7 and 8 of the current application and/or in U.S.patent application Ser. Nos. 15/586,288 and 15/600,794 that are beingincorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) a controller that is configured to determine a cleaning path of aregion of a sidewall of the pool to include less than a predeterminednumber of turns; wherein the predetermined number of turns is associatedwith a cleaning path that mostly includes vertical yaw cleaning pathsegments; (ii) at least one sensor for sensing an actual yaw of the poolcleaner and an actual orientation of the pool cleaner; (iii) at leastone steering element that is configured to move the pool cleaner alongthe cleaning path, during a cleaning process of the certain region; andwherein the controller if further configured to control the at least onesteering element, based on the actual yaw of the pool cleaner. Anon-limiting example of such a pool cleaning robot is illustrated inU.S. patent application Ser. Nos. 15/586,288 and 15/600,794 that arebeing incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) at least one sensor for sensing an actual yaw of the pool cleanerand an actual orientation of the pool cleaner; (ii) at least onesteering element that is configured to move the pool cleaner along acleaning path, during a cleaning process of a certain region of asidewall of the pool and while maintaining contact with the poolsidewall; wherein the cleaning path comprises a cleaning path segmentthat has a cleaning path segment yaw that is a non-vertical yaw; and(iii) a controller that is configured to control the at least onesteering element, based on the actual yaw of the pool cleaner. Anon-limiting example of such a pool cleaning robot is illustrated inU.S. patent application Ser. Nos. 15/586,288 and 15/600,794 that arebeing incorporated herein by reference.

At least one pool cleaning robot of the set may include at least one outof (i) an intake aperture; (ii) a first fluid conduit; (iii) a firstgrille that comprises two or more movable first panes, (iv) a filteringelement that is configured to filter fluid from the intake aperture toprovide filtered fluid. The first fluid conduit is configured to directthe filtered fluid towards the first grille. The first grille isconfigured to output the filtered fluid at a first direction that isresponsive to a position of the two or more movable panes. See, forexample, FIGS. 4A and 4B.

As indicated above different pool cleaning robots of a set may beconfigured to clean different regions of the pool. For example—it isassumed that a first pool cleaning robot and a second pool cleaningrobot are configured to clean different regions of the pool. Under theseassumptions at least one of the following conditions may be fulfilled:

-   -   a. The first pool cleaning robot has cleaning elements that        equal to cleaning elements of the second pool cleaning robot.    -   b. The first pool cleaning robot has cleaning elements that        differ from each cleaning element of the second pool cleaning        robot.    -   c. The first pool cleaning robot has coarser cleaning elements        than the second pool cleaning robot.    -   d. The first pool cleaning robot has finer cleaning elements        than the second pool cleaning robot.    -   e. Only one of the first pool cleaning robot and the second pool        cleaning robot may be configured to climb on a sidewall of the        pool and clean the sidewall of the pool.    -   f. Only one of the first pool cleaning robot and the second pool        cleaning robot may be configured to climb on stairs of the pool.    -   g. Both the first pool cleaning robot and the second pool        cleaning robot may be configured to travel slippery surfaces of        a pool.    -   h. Only one of the first pool cleaning robot and the second pool        cleaning robot may include a directional jet propulsion unit.    -   i. Both the first pool cleaning robot and the second pool        cleaning robot may include a directional jet propulsion unit.        The directional jet propulsion unit may include jet propulsion        directionally adjustable outlet panes.    -   j. The first pool cleaning robot may include a jet propulsion        unit that differs from a jet propulsion unit of the second pool        cleaning robot.    -   k. Only the first pool cleaning robot may be configured to climb        on a sidewall of the pool and clean the sidewall of the pool,        whereon only the second pool cleaning robot may be configured to        clean one or more slippery surfaces of the pool and a third pool        cleaning robot may be configured to clean only a bottom of the        pool.    -   l. The first pool cleaning robot may be configured to clean a        surface of the first grip level and may be not configured to        clean a surface of the second grip level; and wherein the second        pool cleaning robot may be configured to clean a surface of the        second grip level.    -   m. The first pool cleaning robot and the second pool cleaning        robot have different types of brush wheels.    -   n. The first pool cleaning robot and the second pool cleaning        robot may be of different propulsion units.    -   o. The first pool cleaning robot and the second pool cleaning        robot may be of different jet propulsion units.    -   p. The first pool cleaning robot and the second pool cleaning        robot may be of different interface elements for interfacing        with the pool.    -   q. The first pool cleaning robot and the second pool cleaning        robot may be configured to communicate with each other.    -   r. The first pool cleaning robot and the second pool cleaning        robot may be configured to perform a distributed allocation of        cleaning tasks between the first and second pool cleaning        robots.    -   s. The first pool cleaning robot and the second pool cleaning        robot may be configured to repetitively allocate, in a        distributed manner, cleaning tasks between the first and second        pool cleaning robots. The repetitively allocate may be        responsive to at least one out of a state of at least one pool        cleaning robot of the set, a fullness of a battery of at least        one pool cleaning robot of the set, a state of the filtering        elements, any slipping and drifting of the pool cleaning robot        planned cleaning trajectories and/or to the state of the pool.    -   t. Only one of the first pool cleaning robot and the second pool        cleaning robot may be configured to perform waterline cleaning.    -   u. The first pool cleaning robot and the second pool cleaning        robot may be configured to perform waterline cleaning.    -   v. The first pool cleaning robot and the second pool cleaning        robot may be configured to independently recognize pool        underwater features.    -   w. The first pool cleaning robot and the second pool cleaning        robot may be configured to independently generate a map of the        pool.    -   x. The first pool cleaning robot may be configured to merge maps        of the pool generated by the first pool cleaning robot and the        second pool cleaning robot.    -   y. Only one of the first pool cleaning robot and the second pool        cleaning robot may be configured to independently recognize pool        underwater features.    -   z. The first pool cleaning robot and the second pool cleaning        robot may be configured to determine a spatial relationship        between the first and second pool cleaning robots.    -   aa. Only one of the first pool cleaning robot and the second        pool cleaning robot may be configured to determine a spatial        relationship between the first and second pool cleaning robots.    -   bb. The first pool cleaning robot may be configured to change a        communication parameter related to communication attempts with        the second pool cleaning robot when the first pool cleaning        robot reaches a demarcation between regions allocated to the        first and second pool cleaning robots.    -   cc. The first pool cleaning robot may be configured to determine        a communication parameter related to communication attempts with        the second pool cleaning robot based on a distance between the        first pool cleaning robot and the second pool cleaning robot.    -   dd. The first pool cleaning robot may be configured to determine        a communication parameter related to communication attempts with        the second pool cleaning robot based on a distance between the        first pool cleaning robot and a border of a region of the pool        that may be allocated to the second pool cleaning robot.    -   ee. The first pool cleaning robot may include at least one        sensor for sensing locations of cables connected to the first        and second pool cleaning robots.    -   ff. The at least one sensor for sensing locations of connected        pool cleaner cables may include a repetitive pre-configuring of        the propagation of the cables so that they do not entangle and        twist with one another.    -   gg. At least one of the first pool cleaning robot and the second        pool cleaning robot may be configured to exit from the pool        without human intervention.    -   hh. The first pool cleaning robot may be configured to assist in        an exit process of the second pool cleaning robot from the pool.    -   ii. The first pool cleaning robot may be configured to push the        second pool cleaning robot during a cleaning operation of the        second pool cleaning robot.    -   jj. The first pool cleaning robot may be configured to pull the        second pool cleaning robot during a cleaning operation of the        second pool cleaning robot.    -   kk. The first pool cleaning robot may be configured to climb on        the second pool cleaning robot.    -   ll. The first pool cleaning robot may be configured to        detachably connect to the second pool cleaning robot.    -   mm. The first pool cleaning robot may be configured to recharge        the second pool cleaning robot.    -   nn. The first pool cleaning robot may be configured to direct at        least one jet of fluid towards the second pool cleaning robot.    -   oo. The first pool cleaning robot may be configured to direct at        least one jet of fluid towards dirt accumulated in wall and        floor corners.    -   pp. The configured to direct at least one jet of fluid towards        wall and floor corners may include automatically rotating        directional fluid jets outlet panes.    -   qq. The first pool cleaning robot may be configured to travel        while in a horizontal position on vertical pool sidewalls while        maintaining its yaw.    -   rr. The first pool cleaning robot may be configured to        maintaining its yaw while countering constant gravitational        downward forces.    -   ss. The first pool cleaning robot may be a cordless pool        cleaning robot.

FIG. 1A illustrates a pool 10 that has a flat bottom and three regionsthat are allocated to a set of pool cleaning robots that includes threedifferent pool cleaning robots.

The set may fulfill any of the conditions listed in the specificationand/or drawings of the current patent application.

First pool cleaning robot 21 is configured to clean a region of the poolthat includes a first bottom portion 31 and a first sidewall portion31′. First pool cleaning robot 21 follows a cleaning path 41 forcleaning first bottom portion 31 and follows a cleaning path 41′ forcleaning first sidewall portion 31′.

Second pool cleaning robot 22 is configured to clean a region of thepool that includes a second bottom portion 32 and a second sidewallportion 32′. Second pool cleaning robot 22 follows a cleaning path 42for cleaning second bottom portion 32 and follows a cleaning path 42′for cleaning second sidewall portion 32′.

Third pool cleaning robot 23 is configured to clean a region of the poolthat includes a third bottom portion 33 and a third sidewall portion33′. Third pool cleaning robot 23 follows a cleaning path 43 forcleaning third bottom portion 33 and follows a cleaning path 43′ forcleaning third sidewall portion 33′.

While FIG. 1A illustrates raster scan cleaning paths, any of the poolcleaning robots may follow any other cleaning paths—including randomcleaning paths, pseudo-random cleaning paths, and the like. The cleaningpaths may change over time and/or may be dependent on the status of thepool and/or on the structure of the pool (including obstacles) and/or ofthe pool cleaning robot. The cleaning path of one pool cleaning robotmay be the same as (or may differ from) the cleaning path of anotherpool cleaning robot.

It is expected that one of more of the pool cleaning robots is scheduledto clean the other three sidewalls of the pool and maybe the stairs 12.

FIG. 1A also illustrate borders 35 and 36 between the first, second andthird segments.

It should be noted that any other regions may be defined. One or more ofthe regions may include only a sidewall area, only a bottom area or acombination thereof.

The pool cleaning robots may move and/or perform cleaning operationsbased on the locations of obstacles such as drains 17 and/or lightelements and/or return water jets 19.

FIG. 1A does not show any cords that are connected to any of the poolcleaning robots. Any pool cleaning robot may be connected to a cord(which is not shown for simplicity of explanation), or may be a cordlesspool cleaning robot.

FIG. 1B illustrates the first pool cleaning robot 21 as connected viafirst cord 39 to first power supply unit 25, the second pool cleaningrobot 22 as connected via second cord 38 to second power supply unit 26,and the third pool cleaning robot 23 as connected via third cord 37 tothird power supply unit 27. The different power supply units may beconnected at any position in proximity to the pool. The cable lengthsare illustrative and various cable lengths may be used.

In FIG. 1B the power supply units are positioned along the same side ofthe pool. In FIG. 1B the first pool cleaning robot is also configured toperform a waterline cleaning process by following waterline cleaningpath 41″.

FIG. 1C illustrates the first pool cleaning robot 21 as connected via afirst cord to a first power supply unit 25, the second pool cleaningrobot 22 as connected via a second cord to second power supply unit 26,and the third pool cleaning robot 23 as connected via third cord 37 tothird power supply unit 27. The different power supply units may beconnected at any position in proximity to the pool. In FIG. 1C the powersupply units are positioned along three different sides of the pool.

There may be defined an overlap area. FIG. 1D illustrates that thesecond pool cleaning robot cleans an overlap area 34 that expands intofirst bottom portion 31 by following cleaning path 42″. The overlap areamay have any shape and/or size. If first pool cleaning robot 21 isallocated to clean the first bottom portion 31 and first sidewallportion 31′ it may be regarded as an “invaded” pool cleaning robot—andit is notified about the cleaning of the overlap area- to preventcollisions.

Although the said “invaded” pool cleaning robot may seem to betraversing into another pool cleaner bottom or wall portions, the entryinto the overlap area 34 is important and may be governed by a specialdivision of task cleaning program to ensure that the overlap areas arecleaned by either pool cleaners without collisions, entangled cables, orthe leaving behind of an uncleaned dirty strip. Path 42″ depicts anentry along the travelling path that runs along the width section of thepool. Also see 16 in FIG. 1A where the traversing may occur in alongitudinal path in relation to the pool lengths (not shown).

The cleaning regions that are allocated to the different pool cleaningrobot may change over time.

FIG. 1E illustrates a substantially shape preserving change in which allbottom portions remain rectangular—but the third bottom portionincreases to provide an updated third bottom portion 33″ while thesecond bottom portion decreases to provide an updated second bottomportion 32″. Border 36 is shifted to the left.

FIG. 1F illustrates a substantially shape non-preserving change in whichsecond and third bottom portions changes their shape from rectangular totrapezoid. The the third bottom portion increases to provide an updatedthird bottom portion 33″ while the second bottom portion decreases toprovide an updated second bottom portion 32″. Border 36 is rotatedclockwise.

The said shape non-preserving changes may be particularly pertinent tocircular shaped pools, kidney shapes, free-style pond type contouredpools and the like.

FIG. 1G illustrates different collision avoidance maneuvers.

The leftmost part of FIG. 1G illustrates the first pool cleaning robot21 as propagating to the right towards border 35 and the second poolcleaning robot 22 as propagating upward along border 35. Unless one ofthe pool cleaning robots changes his route or slows down—the poolcleaning robots may collide.

The potential collision may be detected by one or more of the poolcleaning robots using any sensor—for example an image sensor, aproximity sensor and the like. The potential collision may be sensed byanother pool cleaning robot and/or another sensor that is not located on(or within) a pool cleaning robot.

One or more of the pool cleaning robots may be informed, over acommunication link, about the potential collision.

The first and/or second pool cleaning robots may inform the other poolcleaning robot of the pair that the distance between them is (or isabout to be) too small and/or that they are in a collision path.

The first and/or second pool cleaning robot may wait for a response fromthe other pool cleaning robot of the pair—and if such a response doesnot arrive—may send another alert, increase the power and/or therepetition rate and/or the carrier frequency and/or the modulation ofthe communication until receiving a response from the other poolcleaning robot or determining that a communication failure occurred.

In case of a communication failure the pool cleaning robot thatattempted to communicate the may perform a collision avoidance maneuverwithout counting on the other pool cleaning robot to perform such acollision avoidance maneuver.

It should be noted that both pool cleaning robots may perform acollision avoidance maneuver.

It should be noted that a pool cleaning robot may perform a collisionavoidance maneuvers even without communicating with the other poolcleaning robot of the pair.

FIG. 1G illustrates some non-limiting examples of collision avoidancemaneuvers—including (from left to right) stopping the progress of thefirst pool cleaning robot 21, changing the direction of progress of thefirst pool cleaning robot (for example moving away from the border 35),and changing the direction of progress of the second pool cleaning robot(for example moving away from the border 35). Movement away from border35 may include a linear or non-linear movement at any direction thatincreases the distance between the pool cleaning robot and the border.

It should be noted that one or more pool cleaning robot may pass theborder—and clean an overlap area. This may involve notifying the“invaded” pool cleaning robot about the overlap area cleaning process.

FIG. 2A illustrates first, second and third pool cleaning robots 21, 22and 23 as well as a pool 100 that has a flat bottom portion 101 followedby a sloped bottom portion 102, a hopper 103 and sidewalls 104, 105 and106 (as well as few unnumbered sidewalls).

Moving along sloped bottom portion 102 and/or cleaning the sloped bottomportion 102 may be challenging—especially when the grip level of thesloped bottom portion is low. Nevertheless, moving along a flat surface101 may be equally challenging if the flat area is slippery. Second andthird pool cleaning robots 22 and 23 may propagate along the slopedbottom portion 102. First pool cleaning robot 21 may or may notpropagate and/or or clean the sloped bottom portion 102.

An area may be regarded as slippery if its grip level or theco-efficient of friction of the pool cleaning robot is less than 1 orthat the movement of the pool cleaning robot is measured to be, say,half than a certain ideal nominal speed of, say for example, 14 metersper minute

A flat area may be regarded as an area that has a slope between zero andten degrees—and the like.

In FIG. 2A, first pool cleaning robot 21 moves along (and/or cleans)flat bottom portion 101, second pool cleaning robot 22 moves along(and/or cleans) sloped bottom portion 102, and third pool cleaning robot23 moves along (and/or cleans) hopper 103.

The sidewall of the pools may be cleaned by one or more pool cleaningrobots of the set.

FIG. 2A does not show any cords that are connected to any of the poolcleaning robots. Any pool cleaning robot may be connected to a cord(which is not shown for simplicity of explanation), or may be a cordlesspool cleaning robot.

Because dirt in pools tends to propagate by gravity to the lower regionsof a pool, slopes and deep ends may be slippier than other areas. Thereare no definite rules on this and the flat regions may be equallyslippery due to dirt accumulation that may also be a result of shocktreatments such as, but not exclusively, the use of flocculants. It iscommon for a pool cleaning robot 23 to not be able to effectively cleanarea 103 let alone exit that area and climb back uphill on slope 102.Within the framework of a set of pool cleaning robots, the second poolcleaning robot 22 or 21 may possess special brushes and/or propulsionjets that allow it to descend on a slippery slope 102 to clean area 103and exit back to area 102 or 101. FIGS. 9,16 and 17 further depictadditional salvage tasks of extracting pool cleaning robot 23 from area103 or 102.

FIG. 2B illustrates (i) first, second and third pool cleaning robots 21,22 and 23, (ii) first, second and third power supply units 26, 27 and28, (iii) first, second and third cords 39, 38 and 37, (iv) a centralpower supply unit 28, and (v) a pool 100 that has a flat bottom portion101 followed by a sloped bottom portion 102, a hopper 103 and sidewalls104, 105 and 106 (as well as few unnumbered sidewalls).

Central power supply unit 28 supplies power to the first, second andthird power supply units 39, 38 and 37. First, second and third powersupply units 39, 38 and 37 are connected via first, second and thirdcords 39, 38 and 37 to first, second and third pool cleaning robots.

First pool cleaning robot 21 is configured to clean flat bottom portion101. The first pool cleaning robot 21 follows a zig-zag cleaning path111 for cleaning the flat bottom portion 101.

Second pool cleaning robot 22 is configured to clean sloped bottomportion 102. The second pool cleaning robot 22 follows a zig-zagcleaning path 112 for cleaning the sloped bottom portion 102.

Third pool cleaning robot 23 is configured to clean hopper 103. Thethird pool cleaning robot 23 follows a zig-zag cleaning path 113 forcleaning hopper 103.

Fourth pool cleaning robot 24 is configured to clean sidewalls 104, 105and 106 as well as a narrow flat strip between sidewalls 104 and 105.The fourth pool cleaning robot 24 follows a zig-zag cleaning path 114for cleaning the sidewalls 104, 105 and 106.

Fourth pool cleaning robot 24 is illustrated as a cordless pool cleaningrobot.

First, second and third pool cleaning robots may or may not cleansidewalls. For example—it may be assumed that first, second and thirdpool cleaning robots may not clean sidewalls and/or that first poolcleaning robot 21 may not clean sloped bottom portion 102.

While FIG. 2B illustrates zig-zag cleaning paths, any of the poolcleaning robots may follow any other cleaning paths—including randomcleaning paths, pseudo-random cleaning paths, and the like. The cleaningpaths may change over time and/or may be dependent on the status of thepool and/or on the structure of the pool (including obstacles) and/or ofthe pool cleaning robot. The cleaning path of one pool cleaning robotmay be the same as (or may differ from) the cleaning path of anotherpool cleaning robot.

It is expected that one of more of the pool cleaning robots (for examplefourth pool cleaning robot 24) may be scheduled to clean the other threesidewalls of the pool 100.

FIG. 3 illustrates various pool cleaning robots that may form a set ofpool cleaning robots. In this specification, a set may also be definedas a cluster or multitude or multiple or flock of pool cleaners and thelike.

Pool cleaning robot 120 includes a maneuverable handle 122, a PVCbristled brush wheel 121, outlets 124 of a water jet propulsion unit,and interfacing elements such as wheels 127 and track 129.

Pool cleaning robot 130 includes a maneuverable handle 122, a PVA spongebrush wheel 131, outlets 134 of a jet propulsion unit, and interfacingelements such as wheels and a track.

Pool cleaning robot 140 includes (i) a maneuverable handle 142, (ii) ahybrid brush wheel that includes PVA sponge brush wheel portions 141 andPVC brush wheel portions 142, (iii) side brushes 143 and 144, and (iv)outlets 147 of a jet propulsion unit, and (v) interfacing elements suchas wheels and a track.

Pool cleaning robot 150 includes (i) a maneuverable handle 142, (ii) ahybrid brush wheel that includes PVA sponge brush wheel portions 141 andPVC brush wheel portions 142, (iii) side brushes 143, 144, 145 and 146,(iv) an auxiliary brush 146′, and (v) interfacing elements such aswheels and a track.

Pool cleaning robot 150 depicts a double brush wheel 142 that isseparated by a sleeve insert (not numbered). By comparison to poolcleaners 120,130, and 160, pool cleaner 150 can rotate 360 degrees ineach direction by means of an additional drive motor for moresophisticated maneuvering abilities.

Pool cleaning robot 150 includes (i) a handle, (ii) a brush wheel 161that may have any of the said brush types (iii) sensors—such as acamera- and especially a detachable camera, and (iv) interfacingelements such as wheels and a track.

Pool cleaner 160 includes any type cleaning brush 161 and a cameracompartment 169 that may further comprise LED lighting, laserrangefinder, acoustic sensors and the like.

FIGS. 4B and 4C illustrate a pool cleaning robot 200 of the set thatincludes a (i) housing 201, and a water jet propulsion unit thatincludes (ii) pump and fluid distribution unit 232 that is fed withfiltered or unfiltered fluid via fluid conduit 231 (either from a fluidintake or from the filtering unit—see reference number 230); (iii)additional fluid conduits 233, 234, 235 and 236, (iv) output fluidinterfaces such as side fluid output units 207 and upper-rear fluidoutput units 206.

Each output fluid interface 207 may or may not control the direction ofthe fluid jet 208 that it outputs. Each output fluid interface 206 mayor may not control the direction of the fluid jet 209 that it outputs.

For example—each output fluid interface may include a grille thatincludes two or more movable first panes that may be moved by one ofmore motors thereby determined the position and/or orientation of thetwo or more movable panes- and the direction of the jet of fluidoutputted from the output fluid interface.

FIG. 4A illustrates the pool cleaning robot 200 as climbing a sidewall211 of a pool towards the waterline 214 using jets of fluid 209 that mayalso perform a sideways waterline cleaning routine on the entire (orpartial) exemplary waterline 41″ in FIG. 1B.

FIG. 5 illustrates pool cleaning robot 300 as including an arm 301 thatextends from housing 322 and is connected to one or more brushingelements such as external brush 29.

Arm 301 may include one or multiple joints and one or more segments thatare connected to the joints. Pool cleaning robot 300 may include one ormore motors and/or control elements that control the position of arm 301and external brush 302 that is connected to the arm 301.

Pool cleaning robot 300 may be configured to position the external brush302 at a position that allows external brush 302 to clean surfaces thatare above the housing 322.

FIG. 5 illustrates an underwater staircase 311 that includes four stairsthat includes horizontal surfaces and vertical surfaces. FIG. 5 alsoillustrates a bottom of the pool 312 on which pool cleaning robot 300 ispositioned (and may optionally hover above) while arm 302 cleans one ormore surfaces out of horizontal surfaces and vertical surfaces. Arm 302may include telescopic bars, extendable or retractable bars, elastic,and/or non-elastic segments.

In FIG. 5 external brush 302 faces a horizontal surface. The externalbrush 302 may be oriented at any angle in relation to the horizon. Forexample—when cleaning any one of vertical surfaces the external brush302 may be vertically oriented.

It is noted that during the cleaning of any of said surfaces the poolcleaning robot 300 may maintain static by countering any force appliedon the external brush 302 by any cleaned surface using fine-tuned fluidjets.

Pool cleaning robot 300 may also hover above any surface illustrated inFIG. 5 while cleaning one or more stairs. It is noted that while bottomleft and/or bottom right brushes clean one stair the arm 302 can be usedto clean another stair.

FIG. 5 also illustrates an interface such as ring 321 for connecting thepool cleaning robot to an extracting device.

FIG. 6A illustrates a pool cleaning robot 400 that is configured toperform leaf skimming waterline cleaning. A non-limiting example of sucha pool cleaning robot is illustrated in USA application 2016/0060887which is incorporated herein by reference. The pool cleaning robot isalso configured to clean the bottom of the pool or any other part of thepool. Pool cleaning robot 400 may be connected to a cord or may becordless.

FIG. 6D illustrates an illustrates a process during which anotherembodiment of a leaf skimming waterline pool cleaning robot 400propagates from being at non-inverted position (331) at the bottom ofthe pool, until (after rotating by 180 degrees while floating towardsthe waterline 340) the pool cleaning robot 400 is positioned inproximity to the waterline 340 and is in an inverted position (position334)—so that the skimmer 160 is positioned above housing 90. Positions332 and 333 are intermediate positions of the pool cleaning robot 400during the process.

FIGS. 6B and 6C illustrate cordless pool cleaning robots 500 and600—having water jet propulsion units that clean a sidewall. Poolcleaning robot 500 has a fixed handle 501 and pool cleaning robot 600does not have any handle. In FIG. 5 the jet propulsion module isillustrated as having side and top apertures 502 and 503. Other parts ofthe jet propulsion unit are not shown.

FIG. 7 illustrates a horizontal cleaning path 721 that is followed bypool cleaning robot 720 while cleaning sidewall 710 whilst countering anatural downward gravity pull.

FIG. 8 illustrates a non-vertical cleaning path 722 that is followed bypool cleaning robot 720 while cleaning sidewall 710 and bypassing asidewall obstacle 711.

FIG. 9 illustrates pool cleaning robot 822 and pushing pool cleaningrobot 821 that is stuck on a main drain 802 of a pool.

FIG. 10 illustrates different filtering units.

Filtering unit 1000 includes a base 1002 and two frames 1010 and 1020that support replaceable filtering panels such as 1011 and 1012(filtering panels or cartridges 1011 are coarser than filtering panels1012). Fluid enters the filtering panels via apertures (notshown—concealed by the frames) formed in base 1002.

Filtering unit 1003 includes a base 1004, and two bag type filteringcomponents 1020. Fluid enters the filtering components 1020 viaapertures 1021 formed in base 1004.

Different pool cleaning robots of the set may have different filteringunits and/or may have different filtering, nets that may becharacterized by pore sizes, assembled in their filtering units.

One or more pool cleaning robots of the set may be configured to cleanthe same region of the pool. They may clean the same region at differentmanners or at the same manner.

FIG. 11 illustrates first and second pool cleaning robots as cleaningpool region 51. Another region of the pool 33 may be cleaned by anotherpool cleaning robot of the set.

FIG. 11 illustrates the second pool cleaning robot 22 as following thefirst pool cleaning robot 21 and both follow the same raster scancleaning path 61. It should be noted that different pool cleaning robotsmay follow different cleaning paths even when cleaning the same regionof the pool.

The first and second pool cleaning robots may clean the same region atthe same time, at different points of time that are proximate to eachother or that are substantially different from each other. There may beno-overlap, a partial overlap or non-overlap between the cleaning periodof the region by the different pool cleaning robots

If the first and second pool cleaning robots clean the same region atdifferent manners. The first pool cleaning robot may be configured toperform a preliminary cleaning of the region and the second poolcleaning robot may be configured to perform a supplementary follow upcleaning of the region. The preliminary cleaning may be faster, sloweror of the same duration as the supplementary cleaning. The preliminarycleaning may be coarser, finer or of the same granularity as thesupplementary cleaning.

FIG. 11 illustrates that the second pool cleaning robot 22 is closeenough to the first pool cleaning robot 21 so that it may collect debrisof a cloud 71 of debris that is elevated from the bottom of the pool bythe first pool cleaning robot 72. Both pool cleaners or a set may alsotravel side by side along travel paths.

FIG. 12 illustrates second pool cleaning robot 22 that is representativeas comprising standard pool cleaner operating components including adedicated opening and conduit 264 for collecting unfiltered fluid anddebris from the cloud of debris 71—and to filtering unit 252. Thisopening may be provided in addition to one or more openings formed atthe bottom of the housing. FIG. 12 also illustrates controller 253,impeller 258, power supply unit 261, pump motor 257 for rotating theimpeller, housing 251 that includes a bottom aperture and a top aperture259 (allowing fluid driven by the impeller to exit the housing), drivemotor and gear 254 that may include a non-return valve control deviceopening and closing 264 as needed (not shown), and communication module260.

FIG. 13 illustrates first pool cleaning robot 21 as including adetachable module 250—such as but not limited to a detachable sensor(e.g.: a camera) that may comprise inductive electrical and datatransfer connections (not shown). FIG. 13 also illustrates filteringunit 252, controller 253, impeller 258, pump motor 257 for rotating theimpeller, housing 251 that includes a bottom aperture 256 and a topaperture 259, drive motor and gear 254, power supply unit 261, andcommunication module 260.

FIG. 14 illustrates first pool cleaning robot 22 as including adetachable module 250—such as but not limited to a detachable battery sothat while one set of charged batteries may be inserted into module 250slot (not shown). FIG. 14 also illustrates filtering unit 252,controller 253, impeller, pump motor for rotating the impeller, ahousing that includes a bottom aperture and a top aperture, drive motorand gear 254, and communication module 260.

FIG. 15 illustrates first pool cleaning robot 21 as including a cordsensor 262 that may have a field of view that is directed upwards—andmay be large in order to image cords of one of more pool cleaning robotsof the set. The cord sensor 262 may be a camera that may in turn bedetachable and fitted onto another pool cleaning robot. It is coupled tocontroller 253. FIG. 13 also illustrates filtering unit 252, impeller,pump motor, a housing that includes a bottom aperture and a topaperture, drive motor and gear 254, and communication module 260.

FIG. 16 illustrates first pool cleaning robot 21 as pushing second poolcleaning robot 22—either by direct contact between the housings of thetwo pool cleaning robots—or by an interfacing element such as a rod 265.The interfacing element may be static or may be dynamic—it may extendoutside the housing, extend its length, or otherwise change its shapeand/or size when pushing another pool cleaning robot.

FIG. 17 illustrates first pool cleaning robot 21 as pulling second poolcleaning robot 22—by an interfacing element such as locked and unlockedconnectors 268.

FIG. 18 illustrates an exchange of a filter between first and secondpool cleaning robots. Each one of first and second pool cleaning robotsmay store multiple filters—such as filters 271, 272 of first poolcleaning robot 21, filters 274 and 275 of second pool cleaning robot22—and filters 273 that is sent from first pool cleaning robot 21 tosecond pool cleaning robot 22.

FIG. 18 illustrates rails 1169 for supporting the filters, first filteropening 1160 of second pool cleaning robot 22 for receiving filter 1170,and a second filter opening. First filter opening 1160 is equipped witha first door 1164 and a spring mechanism 1166 that allows the first door1164 to open when filter 1170 is inserted to the pool cleaning robot 22and to be closed (thereby closing the first filter opening 1160) afterthe filter is inserted. Second filter opening 1162 is equipped with asecond door 1168 and a spring mechanism 1169 that allows the second door1168 to open when a filter is extracted/ejected/outputted from the poolcleaning robot 22 and to be closed (thereby closing the second filteropening 1162) after the filter is extracted/ejected/outputted. It isnoted that a filter opening can be closed by the filter itself.

A movement mechanism such as motor with a gear or other interfacingelements may move the filters along the rail. The movement mechanism maybe located within the housing 1102.

FIG. 19 illustrates first pool cleaning robot 21 that climbs over secondsecond pool cleaning robot 22—thereby climbing one stair of a stairway.

FIG. 20 illustrates a user 1200 that interfaces with a mobile device1210 that in turn communicates with first pool cleaning robot 21. Themobile device 1210 may send commands and/or suggested demarcationinformation to the pool cleaning robot and/or may receive informationsuch as status information from the pool cleaning robot.

FIG. 20 also depicts an in-situ wireless programming of a pool cleaneror pool cleaners to create a set. In-situ may be an end user poollocation. For example, an end user may possess one pool cleaner but maywish to upgrade by adding one or more pool cleaning robots to create aset of pool cleaning robots. According to the various components thatthe pool cleaning robots contains (brushes, jets and the like) and eachof their abilities (climb walls, slopes and the like) the end user maynominate a master and/or a slave and initiate a set pool cleaningprogram that overrides the single—unattached—pool cleaning robot. Thewireless programming or wired (not shown) may be performed separately oneach pool cleaning robot A, B . . . n and additional commands mayprogram the entire set so that it can operate in the pool without havingany collisions and/or cable entanglements.

Another option to create and market a set with pre-definedcharacteristics is at the OEM source premises by offering sets withspecific differentiating features. Alternatively or additionally, theset may be assembled at one of its distributors or service centers.Whereby, in any scenario, a user may specify the profile of its pool andthe vendor(s) may tailor-adapt at least two pool cleaning robots tooperate as an optimal set at the said end user premises.

It should be noted that inter communication between pool cleaning robotsmay be achieved by pool cleaning robots that may recognize the poolunderwater features (for example, by optical or acoustic means).

Namely, the pool cleaning robots may recognize their relative positioninside the pool in relation to pool features and in relation to otherpool cleaning robot.

The pool cleaning robots may be able to recognize a pre-demarcated areaor working zone from which the pool cleaner will not trespass to itsneighboring pool cleaner zone.

Each pool cleaning robot may communicate its position to the neighboringpool cleaning robot(s) thereby ensuring that each cleaner remains withinits demarcated zone.

The pool cleaning robots may communicate with each other directly orindirectly. The indirect communication can be executed by usingsubmerged and/or above-water relays or communication modules.

A communication module may be wirelessly coupled to the pool cleaningrobot. The communication module may be wired coupled to a pool cleaningrobot via the cable that is also used for power supply.

A certain communication module may communicate with a certain poolcleaning robot and may communicate with other pool cleaning robots ormay communicate with other communication modules that in turncommunicate with their associated pool cleaning robots.

The inter communication may be achieved by a wireless device (such as aBluetooth® device) located in each Power Supply unit that is positionedoutside the pool (the PS is an electrical device that is not submerged).Each pool cleaning robot is electrically connected and tethered to thePS by means of an electrical cord.

In another embodiment, the pool cleaning robot(s) is/are operated bymeans of on-board rechargeable batteries so the underwaterinter-communication between pool cleaning robots may be achieved byoptical or acoustical means.

The pool cleaning robot 850 may include at least one of the followingelements on-board (see FIG. 22):

a. A hollow body(housing) 851.b. A water intake aperture 852.c. A water outlet aperture 853.d. A hydraulic path 854 stretching between the said intake and outlet.e. A filtering and/or sieving element (such as a filtering unit)positioned inside the said hydraulic path 855.f. A pumping motor 856 (also referred to as pump motor) positioned inthe hydraulic path.g. A driving motor and reduction gears (also referred to as drive motorand gear) 857.h. Travelling wheels (also referred as wheels) 858.i. Wheels connecting shafts 859.j. Pool surface dirt brushes or scrappers (also referred as brushwheels) 860.k. Auxiliary brushing or scrapping member (also referred to as auxiliarybrush wheel) 861.l. Tracks 862.m. Electrical tethered power supply cable (also referred to as cable)863.n. A chargeable battery 864.o. A communication unit for communicating (wirelessly or in a wiredmanner) with a control unit (also referred as a communication module)865.p. One or more sensors 870.q. Image sensor 871—especially an on-board day and/or night camerar. A video device 872 that captures, memorizes locations of poolfeatures or obstacles and calculates the relative angle and distance ofthe robot from these features to further calculate the robot location inthe pool.s. A lighting optical recognition aid unit 873 for nighttime and/or forhigh turbidity conditions that may also employ an infrared light device.t. One or more motion sensors 874 such as an accelerometer and/or agyroscope and/or an inertial measurement unit (IMU) and/or a laser wallrecognition device.u. A turbidity sensor 875.v. A heading direction measurement sensor 876 such as magnetometer,compass, and/or a gyrocompassw. Impact sensors and/or pressure sensors 877x. Pump motor velocity/current sensors 878y. A control box (also referred to as a controller) 879 that may includea processor and cleaning program software.z. Impeller 880aa. A processor 882 that may be configured to perform any mentionedabove calculations. The processor and the controller 879 may becombined. Any reference to a controller may be referred to as areference to a processor or to a combination of controller and aprocessor. The controller and/or the processor may include one or moreintegrated circuits.bb. Memory module 884 for storing programs, commands, allocation ofregions, sensors information, and the like.

Such programs may include, for example, commands whereby when one poolcleaning robot approaches or is travelling towards a demarcation line,the other pool cleaning robot will direct its movement away from thatsaid demarcation line. This will allow each pool cleaning robot toensure cleanliness of the area around or on the demarcation lines.

There may be provided submerged radiation beacons transmitters fortransmitting radiation beacons that represent the limits of the separate

Although the pool cleaning robots are able to inter-communicate andautomatically assign work programs and demarcation zones between them,another embodiment, that is incorporated herein in its entirety, wasdisclosed in Provisional U.S. application No. 62/287,006 dated 26^(th)of Jan. 2016 and in US patent application publication serial number2017/0212523.

This concerns the overriding possibility of allowing the end-user orpool operator to switch off from automatic inter demarcations by thepool cleaning robots to a manual demarcation. This may be achieved by acontrol device that may be a remote control that can be dedicated or byuse of smart phone or mobile devices that comprise screens that maydepict the pool environment.

Manual demarcations may be achieved by use of said control device thatwill enable the user to add features or lines on screen and draw virtualscanning demarcation lines for cleaning zones in the pool, mark specialpool areas that may need special attention by marking that area, markend-point to arrive to at the end of the cleaning cycle, ability tooverrule the preset cycle time and the like.

The pool cleaning robot may be powered by an electrical power cordtethered to an external power supply. It may autonomously exit the poolin order to evacuate the swimming pool area and/or in order to serviceits filtering unit in an external docking station that may be located onthe deck near the pool or it may be located in an underground parkingarea in the pool deck or its environs. See U.S. provisional patent Ser.No. 62/146,335 filing dated Apr. 12, 2015 and the continuation in partof U.S. patent application Ser. No. 14/501,098 filing date Sep. 30, 2014which claims priority from U.S. provisional patent Ser. No. 61/890,260filing date Oct. 13, 2013, and all their ensuing patent applicationsthat are all, for the purpose of this “exiting embodiment”, beingincorporated herein by reference.

The pool cleaning robot may be powered by on-board batteries and mayemploy a submerged docking station for recharging its batteries.Alternatively, it may autonomously exit the pool in order to be chargedby an external docking system.

A cord connected to a pool cleaning robot may include at least one outof transmitters for transmitting electromagnetic information that oncesensed by one or more pool cleaning robots may allow the one or morepool cleaning robots to determine the location of the cord. Thesetransmissions may include a unique identifier or may have any othercharacter (such as carrier frequency) that will enable the pool cleaningrobot to detect that transmission s resulting from the cable—and notfrom another pool cleaning robot. There may be multiple transmittersthat are located at multiple locations along the cord. A single poolcleaning robot may determine the location of any cord. Alternatively—thedetermination may be made in a distributed manner—for example bycomparing the reception parameters of the transmissions of thetransmitter—as received by different pool cleaning robots—atriangulation process or other location finding process may beperformed.

Additionally or alternatively—one or more receivers may be attached tothe cord and the receiver may determine its location by analyzingreceived transmissions from one or more pool cleaning robots.Alternatively—the receiver receives the transmission and sendinformation about the transmission (identifier, source of transmission,reception parameters such as strength, RSSI) to one or more poolcleaning robot and/or to another device for analysis and locationdetermination.

Additionally or alternatively—the cords may be coupled to or include anytype of proximity sensors that may sense that a pair of cords are tooclose to each other—and then send an alert to one or more pool cleaningrobot and/or to another device.

The cord may be coupled to or may include an image sensor for sensingthe location of the pool cleaning robot. The image acquired from theimage sensor may be used to determine the relative position of the cordand the camera.

FIG. 21 illustrates first pool cleaning robot 21 as connected to a cord39 that include transmitter 391 and receiver or sensor 392.

FIG. 21 also illustrates filtering unit 252, controller 253, impeller,pump motor, housing that includes a bottom aperture and a top aperture,drive motor and gear 254, power supply unit 261, and communicationmodule 260.

There may be provided a method for cleaning a pool by a set of robots.The cleaning may be executed simultaneously, in a partially overlappingmanner or in a non-overlapping manner.

The cleaning of the pool may require a participation of the poolcleaning robots of the set. Cleaning a pool using a set of pool cleaningrobots may speed the cleaning period, may improve the cleanliness of thepool.

There may be provided a method for cleaning the pool using only a subsetof the set (that subset may include one or more pool cleaningrobots)—for example when the remaining pool cleaning robot areunavailable—or for any other reason. Cleaning the pool by using only thesubset may be slower and/or less efficient than cleaning the pool usingthe entire set—but this is not necessarily so.

The cleaning may use a set of pool cleaning robots that may be equal toeach other or may differ from each other. The difference may includedifferent hardware components and/or different software, code, firmwareor malware configurations.

FIG. 23 illustrates and example of method 890.

Method 890 may start by an initialization step 895.

The initializing step may include at least one out of:

-   -   a. Allocating cleaning tasks to the pool cleaning robots of the        set.    -   b. Inserting the pool cleaning robot to the pool.    -   c. Configuring one or more pool cleaning robot of the set to        cooperate with other pool cleaning robots of the set.    -   d. Communicating between the pool cleaning robots of the set.    -   e. Recognizing by at least one pool cleaning robot of the set        its location within the pool.    -   f. Performing orientation within the pool of one or more pool        cleaning robot.    -   g. Determining which pool cleaning robot is a master pool        cleaning robot.    -   h. Determining which pool cleaning robot is a slave pool        cleaning robot.    -   i. Determining which pool cleaning robot is not a master or        slave pool cleaning robot.

Initialization step 895 may be followed by step 900 of cleaning a poolusing at least two pool cleaning robots of a set of pool cleaningrobots. The at least two pool cleaning robots may form the entire set ormay form only a sub-set of the set.

In the following list any reference to a set of pool cleaning robots mayalso apply to a sub-set of pool cleaning robots. Thus, any step executedby one or more pool cleaning robot of a set may be executed by one ormore pool cleaning robots of a sub-set of the set. The sub-set includesfewer pool cleaning robot than the set.

Step 900 may include at least one out of the following steps:

-   -   91. Cleaning the pool by a set, wherein the set may include a        first pool cleaning robot and a second pool cleaning robot that        differ from each other by at least one unit out of a propulsion        unit and a cleaning unit; wherein each one of the first pool        cleaning robot and the second pool cleaning robot may include a        filtering unit, a housing, and a controller.    -   92. Cleaning the pool by at least two pool cleaning robots that        differ from each other. The difference may be a difference in a        propulsion unit, a difference in a cleaning unit, a difference        in a sensor, a difference in a controller, and the like. The        pool cleaning robots may include a filtering unit, a housing,        and a controller.    -   93. Cleaning a sidewall of the pool by at least one pool        cleaning robot of the set.    -   94. Performing, by at least one pool cleaning robot of the set,        collision avoidance steps for preventing a collision between the        first pool cleaning robot and the second pool cleaning robot.    -   95. Performing, by at least one of the set, cable entanglement        avoidance steps for preventing an entanglement of a cable        connected to the first pool cleaning robot with a cable        connected to the second pool cleaning robot.    -   96. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot        includes a jet propulsion unit.    -   97. Performing jet propulsion movement by at least one of the        pool cleaning robots of the set.    -   98. Cleaning the pool using at least one out of a PVC brush        wheel and PVA sponge brush wheel.    -   99. Cleaning the pool using a pool cleaning robot that may        include a PVC brush wheel and does not include a Polyvinyl        acetate (PVA) sponge brush wheel.    -   910. Cleaning the pool using a pool cleaning robot that may        include a PVA sponge brush wheel and does not include a PVC        brush wheel.    -   911. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot may        include a sponge brush wheel.    -   912. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot may        include a sponge brush wheel.    -   913. Cleaning the pool using a brush wheel that includes a        sponge brush wheel portion and a PVC brush wheel portion.    -   914. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot        includes a brush wheel that includes a sponge brush wheel        portion and a PVC brush wheel portion.    -   915. Cleaning the pool using the set. The cleaning may include        removing coarser coarser dirt by a first pool cleaning robot and        cleaning finer dirt by a second pool cleaning robot.    -   916. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to hover between a bottom of a pool        floor and a waterline.    -   917. Hovering one or more pool cleaning robots of the set        between any points—such as a bottom of a pool and a waterline.    -   918. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to skim the water surface and then        sink to the bottom floor.    -   919. Skimming the water surface by a pool cleaning robot of the        set, and then sinking the pool cleaning robot to the bottom        floor.    -   920. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to clean different regions of the pool.    -   921. Cleaning different regions of the pool using different pool        cleaning robots.    -   922. Cleaning the pool using the set wherein the first pool        cleaning robot may include a detachable module, wherein the        first pool cleaning robot and the second pool cleaning robot are        configured to interchangeably receive the detachable module.    -   923. Exchanging a detachable module between two pool cleaning        robots of the set. The exchanging may be executed during the        cleaning, before the cleaning or after the cleaning. The        detachable module may include a detachable sensor, a detachable        power source, a detachable communication module, a detachable        controller, and the like.    -   924. Cleaning the pool using the set where in the first pool        cleaning robot and the second pool cleaning robot are configured        to clean a same region of the pool at different manners    -   925. Cleaning the same region of the pool (in an overlapping,        partially overlapping or non-overlapping timing) by pool        cleaning robots of the set. For example—have a first and second        pool cleaning robots clean the same region of the pool.    -   926. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot cooperatively        reallocate cleaning tasks according to failure to complete        cleaning tasks.    -   927. Cooperatively reallocating cleaning tasks, by pool cleaning        robots of the set.    -   928. Cooperatively reallocating cleaning tasks, by pool cleaning        robots of the set according to a failure to complete one or more        cleaning tasks. For example—when a pool cleaning robot        malfunctions and/or from any reasons fails to complete his        cleaning task (for example his progress is too slow and he        cleaned only a part of the task) the pool cleaning robots may        determine which pool cleaning robot (or robots) will finish the        cleaning task—or may decide on any other reallocation of tasks.        The failure to completing tasks are failure to traverse and/or        clean slippery pool surfaces, especially slippery sloped bottom        regions of the pool.    -   929. Cleaning a slippery flat bottom region of the pool by one        or more pool cleaning robots of the set.    -   930. Cleaning a pool by a set of pool cleaning robots that may        include a first pool cleaning robot and a second pool cleaning        robot that differ from each other by at least one unit out of a        propulsion unit and a cleaning unit; wherein each one of the        first pool cleaning robot and the second pool cleaning robot may        include a filtering unit, a housing, a, and a controller.    -   931. Cleaning the pool using the set, wherein the set includes        first and second pool cleaning robots the are configured to        clean different regions of the pool. The configuring may include        programming the regions, programming any instructions that        assist in maintaining the regions by the different pool cleaning        robots, sensing demarcation region beacons or any other mean for        delimiting between the regions.    -   932. Cleaning the pool using the set, wherein a first pool        cleaning robot that has cleaning elements that equal to cleaning        elements of the second pool cleaning robot.    -   933. Cleaning the pool using the set, wherein the first pool        cleaning robot that has cleaning elements that differ from each        cleaning element of the second pool cleaning robot.    -   934. Cleaning the pool using the set wherein the first pool        cleaning robot has coarser cleaning elements than the second        pool cleaning robot.    -   935. Cleaning the pool using the set wherein the first pool        cleaning robot has finer cleaning elements than the second pool        cleaning robot.    -   936. Cleaning the pool using the set. The cleaning may include        climbing on a sidewall of the pool and cleaning the sidewall of        the pool only by one of the first pool cleaning robot and the        second pool cleaning robot.    -   937. Cleaning the pool using the set. The cleaning may include        climbing on stairs of the pool only by one (or by both of) of        the first pool cleaning robot and the second pool cleaning        robot.    -   938. Cleaning the pool using the set wherein both the first pool        cleaning robot and the second pool cleaning robot is configured        to travel slippery surfaces of a pool.    -   939. Travelling over and/or cleaning slippery surfaces of a pool        by one or more pool cleaning robots of the set.    -   940. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot may        include a directional jet propulsion unit.    -   941. Cleaning the pool using the set wherein at least one pool        cleaning robot comprises a directional jet propulsion unit that        includes jet propulsion directionally adjustable outlet panes.    -   942. The cleaning may include adjusting a configuration of a jet        propulsion directionally adjustable outlet panes thereby        changing a direction of propagation of a pool cleaning robot.    -   943. Cleaning the pool using the set wherein the first pool        cleaning robot may include a jet propulsion unit that differs        from a jet propulsion unit of the second pool cleaning robot.    -   944. Moving different pool cleaning robots of the set using jet        propulsion units that differ from each other by shape and/or        size and/or strength, and/or directions of jets, number of jets,        and the like.    -   945. Cleaning the pool using the set wherein only the first pool        cleaning robot is configured to climb on a sidewall of the pool        and clean the sidewall of the pool, wherein only the second pool        cleaning robot is configured to clean one or more slippery        surfaces of the pool and a third pool cleaning robot is        configured to clean only a bottom of the pool.    -   946. Climbing on a sidewall of the pool (or hovering nearby) and        cleaning the sidewall of the pool by one of the pool cleaning        robots of the sets.    -   947. Cleaning one or more slippery surfaces of the pool by one        of the pool cleaning robots of the sets.    -   948. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to clean a surface of the first        grip level and is not configured to clean a surface of the        second grip level; and wherein the second pool cleaning robot is        configured to clean a surface of the second grip level.    -   949. Cleaning surfaces of a first grip level by a pool cleaning        robot that is not suited to clean surfaces of a second grip        level.    -   950. Cleaning surfaces of a second grip level by a pool cleaning        robot that is also suited to clean surfaces of a first grip        level.    -   951. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot have different        types of brush wheels.    -   952. Cleaning the pool by different types of brush wheels.    -   953. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are of        different propulsion units.    -   954. Moving pool cleaning robots within the pool using        propulsion units that differ from each other.    -   955. Cleaning the pool using the set, the first pool cleaning        robot and the second pool cleaning robot are of different        interface elements for interfacing with the pool. The interface        elements may be wheels, tracks, and the like. The wheels may        differ from each other by shape, size, cross section, grip        level, material and the like.    -   956. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to communicate with each other.    -   957. Communicating between pool cleaning robot of the set before        the cleaning, during the cleaning and/or after the cleaning.    -   958. Performing, by pool cleaning robots of the set, a        distributed allocation of cleaning tasks between the first and        second pool cleaning robots.    -   959. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to repetitively allocate, in a distributed manner, cleaning        tasks between the first and second pool cleaning robots.    -   960. Repetitively allocating, in a distributed manner, cleaning        tasks between pool cleaning robots of the set. The repetitions        may be periodic, non-periodic, be triggered by events (failure,        completion of tasks, collision, or cable entanglement danger,        and the like) or in any other manner.    -   961. Different pool cleaning robots of the set (or the same pool        cleaning robot) may participate in different allocations.    -   962. The allocation may involve using any allocation process.    -   963. Repetitively allocating based on a state of at least one        pool cleaning robot of the set.    -   964. Repetitively allocating based on a fullness of a battery of        at least one pool cleaning robot of the set.    -   965. Repetitively allocating based on a state of the filtering        elements of the pool cleaning robots.    -   966. Repetitively allocating based on slipping and drifting of        the pool cleaning robot planned cleaning trajectories.    -   967. Repetitively allocating based on a slipperiness state of        the pool.    -   968. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot is        configured to perform sideways waterline cleaning.    -   969. Performing sideways waterline cleaning by any number of        pool cleaning robots of the set.    -   970. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to perform waterline cleaning.    -   971. Performing waterline cleaning by any number of pool        cleaning robots of the set.    -   972. Recognizing, by any number of pool cleaning robots of the        set, pool underwater features.    -   973. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to independently recognize pool underwater features.    -   974. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to independently (or non-independently) generate one or more        maps of the pool or any part of the pool.    -   975. Independently or non-independently generating one or more        maps of the pool (or any part of the pool) by any number of pool        cleaning robots of the set.    -   976. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to merge maps of the pool (or any        part of the pool) generated by the first pool cleaning robot and        the second pool cleaning robot.    -   977. Merging maps of the pool (or any part of the pool) that are        generated by pool cleaning robots of the set.    -   978. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot is        configured to independently recognize pool underwater features.    -   979. Independently recognizing pool underwater features by any        number of pool cleaning robots of the set.    -   980. Cleaning the pool using the set wherein the first pool        cleaning robot and the second pool cleaning robot are configured        to determine a spatial relationship between the first and second        pool cleaning robots.    -   981. Determining spatial relationship between one or more pool        cleaning robots of the set. The determination may be done by one        or more pool cleaning robots of the set, and/or by one or more        device that differs from the pool cleaning robots of the set.    -   982. Cleaning the pool using the set wherein only one of the        first pool cleaning robot and the second pool cleaning robot is        configured to determine a spatial relationship between the first        and second pool cleaning robots.    -   983. Changing, by at least one pool cleaning robot, at least one        communication parameter related to communication attempts        (duration, strength, repetition rate, carrier frequency, and the        like) between pool cleaning robots when at least one of the        following occurs:    -   984. A pool cleaning robot reaches a demarcation between regions        allocated to the different pool cleaning robots.    -   985. A distance or a change in a distance between pool cleaning        robots.    -   986. A distance or a change in a distance between a pool        cleaning robot and a border of a region of the pool that is        allocated to another pool cleaning robot.    -   987. Cleaning the pool using the set wherein the first pool        cleaning robot may include at least one sensor for sensing        locations of cables connected to the first and second pool        cleaning robots.    -   988. Sensing by at least one sensor of at least one pool        cleaning robot, at least one location of at least one cable        connected to the first and second pool cleaning robots.    -   989. Communicating between pool cleaning robots and or between a        pool cleaning robot and another system information about the        sensed location of the one or more cables connected to the one        or more pool cleaning robots.    -   990. Repetitively configuring the propagation of the cables so        that they do not entangle and twist with one another.    -   991. Cleaning the pool using the set wherein at least one of the        first pool cleaning robot and the second pool cleaning robot is        configured to exit from the pool without human intervention.    -   992. Exiting from the pool by any number of pool cleaning robots        of the set without human intervention.    -   993. Assisting, by a first pool cleaning robot, in an exit        process of a second pool cleaning robot from the pool.    -   994. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to push the second pool cleaning        robot during a cleaning operation of the second pool cleaning        robot.    -   995. Pushing one pool cleaning robot by another pool cleaning        robot during a cleaning operation (before the cleaning operation        and/or after the cleaning operation).    -   996. Pulling one pool cleaning robot by another pool cleaning        robot during a cleaning operation (before the cleaning operation        and/or after the cleaning operation) of at least one of the pool        cleaning robots.    -   997. Mechanically and/or via fluid jets affecting, by at least        one pool cleaning robot, a movement and/or a cleaning process        applied by another pool cleaning robot.    -   998. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to pull the second pool cleaning        robot during a cleaning operation of the second pool cleaning        robot.    -   999. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to climb on the second pool        cleaning robot.    -   9100. Climbing, by one pool cleaning robot, over another pool        cleaning robot.    -   9101. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to detachably connect to the second        pool cleaning robot    -   9102. Detachably connecting one or more pool cleaning robots to        each other.    -   9103. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to recharge the second pool        cleaning robot.    -   9104. Recharging one pool cleaning robot by another.    -   9105. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to direct at least one jet of fluid        towards the second pool cleaning robot.    -   9106. Directing, from one pool cleaning robot a jet of fluid        towards another pool cleaning robot.    -   9107. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to direct at least one jet of fluid        towards dirt accumulated in wall and floor corners.    -   9108. Directing, by at least one pool cleaning robot, a jet of        fluid towards wall and floor corners. The directing may include        automatically rotating directional fluid jets outlet panes.    -   9109. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to travel while in a horizontal        position on vertical pool sidewalls while maintaining its yaw.    -   9110. Moving a pool cleaning robot, during the cleaning process,        before the cleaning process or after the cleaning process, while        in a horizontal position on vertical pool sidewalls while        maintaining its yaw. The yaw may be maintained while countering        constant gravitational downward forces.    -   9111. Cleaning the pool using the set wherein the first pool        cleaning robot is a cordless pool cleaning robot.    -   9112. Cleaning the pool using the set wherein a first pool        cleaning robot and a second pool cleaning robot are configured        to clean a same region of the pool at different manners.    -   9113. Cleaning a same region by different pool cleaning robots        of the set in different manners. The different manners may        differ from each other by cleaning speed and/or cleaning        efficiency, by the type of debris that is scrubbed, by its        granularity (coarser or finer cleaning), and the like.    -   9114. Cleaning the pool using the set wherein the first pool        cleaning robot is configured to perform a preliminary cleaning        of the region and the second pool cleaning robot is configured        to perform a supplementary cleaning of the region.    -   9115. Cleaning the pool using the set wherein the preliminary        cleaning is faster than the supplementary cleaning.    -   9116. Cleaning the pool using the set wherein the preliminary        cleaning is slower than the supplementary cleaning.    -   9117. Cleaning the pool using the set wherein the preliminary        cleaning is coarser than the supplementary cleaning.    -   9118. Cleaning the pool using the set wherein the second        cleaning robot is configured to follow the first pool cleaning        robot.    -   9119. Cleaning the pool while one pool cleaning robot follows        the path of another pool cleaning robot.    -   9120. Cleaning the pool while one pool cleaning robot does not        follow the path of another pool cleaning robot.    -   9121. Cleaning the pool while one pool cleaning robot maintains        a certain distance from another pool cleaning robot. The certain        distance may be smaller than a length of any one of the pool        cleaning robots, may equal said length or may exceed the length.    -   9122. Cleaning the pool without maintaining a certain distance        between pool cleaning robots.    -   9123. Cleaning the pool using the set wherein the second        cleaning robot is configured to perform the supplementary        cleaning of the region while staying within a cloud of debris        elevated during the preliminary cleaning of the region.    -   9124. Collecting, by one pool cleaning robot, debris that was        elevated from a surface of the pool by another pool cleaning        robot.    -   9125. Cleaning the pool using the set wherein the includes a        master pool cleaning robot and a slave pool cleaning robot.    -   9126. Cleaning the pool using the set wherein the first pool        cleaning robot operates as a master pool cleaning robot during a        certain period of time and wherein the second pool cleaning        robot operates as a slave pool cleaning robot during the certain        period of time.    -   9127. Operating a first pool cleaning robot as a master pool        cleaning robot (at least during a certain period) and operating        a second pool cleaning robot as a slave (at least during a        certain period). The master pool cleaning robot may control the        operations of the slave pool cleaning robot during the certain        period    -   9128. Cleaning different regions of the pool by the master and        slave pool cleaning robot.    -   9129. Cleaning the same region of the pool by the master and        slave pool cleaning robots.    -   9130. Applying, by at least one of the slave and master pool        cleaning robots, collision avoidance maneuvers to prevent        collisions between the slave and master pool cleaning robots.    -   9131. Controlling, by the master pool cleaning robot, at least        one cleaning related operation of the slave pool cleaning robot.        This operation may include cleaning, moving within the pool,        exiting from the pool, performing a backwash, replacing a filter        of the slave cleaning robot, performing a collision avoidance        maneuver, performing a cable entanglement avoidance maneuver,        cleaning a filter of the slave pool cleaning robot, and the        like. The controlling may include commanding, requesting,        suggesting, programming, instructing, code reconfiguring, and        the like.    -   9132. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to instruct the slave pool cleaning        robot to perform cleaning operations within a predefined region        of the pool, and wherein the slave pool cleaning robot is        configured to perform the cleaning operations only within the        predefined region of the pool.    -   9133. Instruct, by the master pool cleaning robot, the slave        pool cleaning robot to perform cleaning operations within a        predefined region of the pool.    -   9134. Performing, by the slave pool cleaning robot, the cleaning        operations only within the predefined region of the pool.    -   9135. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to apply collision avoidance        maneuvers to prevent collisions between the master pool cleaning        robot and the slave pool cleaning robot.    -   9136. Instructing, by the master pool cleaning robot, the slave        pool cleaning robot to apply collision avoidance maneuvers to        prevent collisions between the master pool cleaning robot and        the slave pool cleaning robot.    -   9137. Cleaning the pool using the set wherein the master pool        cleaning robot has cleaning elements that equal to cleaning        elements of the slave pool cleaning robot.    -   9138. Cleaning the pool using the set wherein the master pool        cleaning robot has cleaning elements that differ from cleaning        elements of the slave pool cleaning robot.    -   9139. Cleaning the pool using the set wherein the master pool        cleaning robot has coarser cleaning elements than the slave pool        cleaning robot.    -   9140. Cleaning the pool using the set wherein the master pool        cleaning robot has finer cleaning elements than the slave pool        cleaning robot.    -   9141. Cleaning the pool using the set wherein only one of the        master pool cleaning robot and the slave pool cleaning robot is        configured to climb on a sidewall of the pool and clean the        sidewall of the pool.    -   9142. Climbing a sidewall of the pool by only one of the slave        and master pool cleaning robots.    -   9143. Cleaning the pool using the set wherein only one of the        master pool cleaning robot and the slave pool cleaning robot is        configured to travel slippery surfaces of a pool.    -   9144. Traveling slippery surfaces of the pool by only one of the        slave and master pool cleaning robots.    -   9145. Cleaning the pool using the set wherein both master pool        cleaning robot and the slave pool cleaning robot is configured        to travel slippery surfaces of a pool.    -   9146. Cleaning the pool using the set wherein only one of the        master pool cleaning robot and the slave pool cleaning robot may        include a jet propulsion unit.    -   9147. Using a jet propulsion unit by only one (or both) of the        slave and master pool cleaning robots.    -   9148. Cleaning the pool using the set where in both the master        pool cleaning robot and the slave pool cleaning robot may        include a jet propulsion unit.    -   9149. Cleaning the pool using the set wherein the master pool        cleaning robot may include a jet propulsion unit that differs        from a jet propulsion unit of the slave pool cleaning robot.    -   9150. Cleaning the pool using the set wherein at least one pool        cleaning robot of the set is configured to generate information        about a status of a pool, and wherein the master pool cleaning        robot is configured to allocate a cleaning task to the slave        pool cleaning robot based on the information about the status of        the pool.    -   9151. Generating, by at least one pool cleaning robot of the set        information about a status of a pool. The one or more pool        cleaning robot may include a master pool cleaning robot, a slave        pool cleaning robot or a pool cleaning robot that is neither a        master or a slave.    -   9152. Allocating, by the master pool cleaning robot, a cleaning        task to the slave pool cleaning robot based on the information        about the status of the pool. The status of the pool may include        a cleanliness of the pool.    -   9153. Cleaning the pool using the set wherein the allocating of        the cleaning task may include determining a region of the pool        to be cleaned by the slave pool cleaning robot.    -   9154. Determining, by the master pool cleaning robot, a region        of the pool to be cleaned by the slave pool cleaning robot.    -   9155. Cleaning the pool using the set wherein the allocating of        the cleaning task may include determining a manner of cleaning        of a pool region of the pool to be cleaned by the slave pool        cleaning robot.    -   9156. Determining by the master pool cleaning robot, a manner of        cleaning of a pool region of the pool to be cleaned by the slave        pool cleaning robot.    -   9157. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to receive instructions from        another device regarding an association between different pool        cleaning robots of the sets and the different regions of the        pool.    -   9158. Receiving, by the master pool cleaning robot, instructions        from another device regarding an association between different        pool cleaning robots of the sets and the different regions of        the pool.    -   9159. Amending by the master pool cleaning robot the        instructions or leaving the instructions unlamented.    -   9160. Communicating the instructions to one or other pool        cleaning robots of the set.    -   9161. Receiving responses to the communication from one or more        other pool cleaning robots.    -   9162. Negotiating the instructions with one or more slave pool        cleaning robots.    -   9163. Receiving updates about the status of the pool and/or pool        cleaning robots and updating the instructions.    -   9164. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to receive instructions from        another device regarding an association between different pool        cleaning robots of the set and the different regions of the        pool, and to amend the association based on the status of the        pool.    -   9165. Allocating, by the master pool cleaning robot, a cleaning        task to the slave pool cleaning robot based on a status of the        slave pool cleaning robot and a status of the master pool        cleaning robot, a status of the slave pool cleaning robot.    -   9166. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to allocate a cleaning task to the        slave pool cleaning robot based on at least one out of a status        of the slave pool cleaning robot,    -   9167. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to receive a definition of the        different regions of the pool and to define overlap areas of the        pool that are cleaned, at different points in time, by more than        a single pool cleaning robot.    -   9168. Defining by the master pool cleaning robot overlap areas        of the pool that are cleaned, at different points in time, by        more than a single pool cleaning robot.    -   9169. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to communicate information about        the overlap areas to the slave pool cleaning robot.    -   9170. Communicating, by a master pool cleaning robot,        information about the overlap areas to the slave pool cleaning        robot.    -   9171. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to track a position of the slave        pool cleaning robot.    -   9172. Tracking, by the master pool cleaning robot a position of        the slave pool cleaning robot.    -   9173. Cleaning the pool using the set wherein each pool cleaning        robot of the set is configured to track a position of at least        one other pool cleaning robot of the set.    -   9174. Tracking by one or more pool cleaning robot position (or        positions) of at least one pool cleaning robot of the set.    -   9175. Cleaning the pool using the set wherein the master pool        cleaning robot and the slave pool cleaning robot are configured        to replace roles.    -   9176. Replacing roles between a master pool cleaning robot and a        slave pool cleaning robot.    -   9177. Turning a master pool cleaning robot to a pool cleaning        robot that is neither a master pool cleaning robot or a slave        pool cleaning robot.    -   9178. Turning a slave pool cleaning robot to a pool cleaning        robot that is neither a master pool cleaning robot or a slave        pool cleaning robot.    -   9179. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to receive information about a        location of a cord that is connected to the slave pool cleaning        robot and to allocate a region to be cleaned by the slave pool        cleaning robot based on the information about the location of        the cord that is connected to the slave pool cleaning robot and        based on estimated or actual location of another cord that is        connected to the master pool cleaning robot.    -   9180. Receiving, by a master pool cleaning robot, information        about a location of a cord that is connected to the slave pool        cleaning robot.    -   9181. Allocating, by the master pool cleaning robot, a region to        be cleaned by the slave pool cleaning robot based on the        information about the location of the cord that is connected to        the slave pool cleaning robot and/or based on estimated or        actual location of another cord that is connected to the master        pool cleaning robot.    -   9182. Cleaning the pool using the set wherein the master pool        cleaning robot is configured to sense a location of a cord that        is connected to the slave pool cleaning robot and to allocate a        region to be cleaned by the slave pool cleaning robot based on        the sensed location of the cord that is connected to the slave        pool cleaning robot and based on estimated or actual location of        another cord that is connected to the master pool cleaning        robot.    -   9183. Sensing, by the master pool cleaning robot, a location of        a cord that is connected to the slave pool cleaning robot.    -   9184. Allocating, by the master pool cleaning robot, a region to        be cleaned by the slave pool cleaning robot based on the sensed        location of the cord that is connected to the slave pool        cleaning robot and/or based on estimated or actual location of        another cord that is connected to the master pool cleaning        robot.    -   9185. Cleaning the pool using the set wherein the master pool        cleaning robot may include at least one sensor that is not        included in the slave pool cleaning robot.    -   9186. Cleaning the pool using the set wherein the master pool        cleaning robot may include an image sensor that is not included        in the slave pool cleaning robot.    -   9187. Cleaning the pool using the set wherein the master pool        cleaning robot may include an image sensor that is a detachable        modular sensor to be reattached to a slave pool cleaning robot.    -   9188. Cleaning the pool using the set wherein slave pool        cleaning robot and the master pool cleaning robot are configured        to perform cable entanglement avoidance steps for preventing an        entanglement of a cable connected to the slave pool cleaning        robot with a cable connected to the master pool cleaning robot.    -   9189. Performing, by at least one pool cleaning robot, cable        entanglement avoidance steps for preventing an entanglement of a        cable connected to the slave pool cleaning robot with a cable        connected to the master pool cleaning robot.

FIG. 24 illustrates method 2000.

Method 2000 may include step 2010 of programming a pool cleaning robotto participate in a cleaning of a pool by a set of pool cleaning robots.The programming may include updating the programming, programming thepool cleaning robot in a remote manner—for example sending programminginstructions over a communication link, programming the pool cleaningrobot by sending programming commands over a wired connection, insertingto the pool cleaning robot a preprogrammed non-transitory computerreadable medium, downloading programming instructions to the poolcleaning robot and the like.

Step 2010 may include any one out of:

-   -   a. Programming the pool cleaning robot to cooperate with at        least one other pool cleaning robot of a set of pool cleaning        robots that are configured to clean the same pool.    -   b. Programming the pool cleaning robot to receive instructions        from a master pool cleaning robot.    -   c. Programming the pool cleaning robot to send instructions to a        slave pool cleaning robot.    -   d. Programming the pool cleaning robot to send instructions to a        slave pool cleaning robot.    -   e. Programming the pool cleaning robot to perform (or        participate in a performing of) any one of the steps of method        890.    -   f. Programming the pool cleaning robot to perform any operation        that the pool cleaning robot is configured to do—according to        the specification.

Step 2010 may be followed by step 2020 of verifying or checking that theprogramming succeeded. This may include monitoring the operations of thepool cleaning robot during a cleaning process, before a cleaningprocess, by using a verification tool, and the like.

Any of the cleaning processes may be applied to one or more regions thatcover the entire pool or only some part (or some parts) of the pool.

Unless explicitly stated otherwise (for example “only one of the firstand second pool cleaning robot is configured to . . . ”) any abilityallocated to the first pool cleaning robot may be an ability of thesecond pool cleaning robot or any number of pool cleaning robots of theset. Unless explicitly stated otherwise any operation executed by thefirst pool cleaning robot may be executed by another pool cleaning robotof the set. For example—if the specification refers to a first poolcleaning robot that pushes a second pool cleaning robot—then the secondpool cleaning robot may push the first pool cleaning robot. If the firstpool cleaning robot is regarded as a master pool cleaning robot—then anyother pool cleaning robot of the set may be a master pool cleaning robotand the first pool cleaning robot (and any number of pool cleaning robotof the set) may become slave pool cleaning robot.

A pool cleaning robot may be a master in correction to some operations(for example allocation of regions) but a slave pool cleaning robot inregard to other operations.

The terms “region”, “portion” and “area” are used in an interchangeablemanner.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims.

Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under”and the like in the description and in the claims, if any, are used fordescriptive purposes and not necessarily for describing permanentrelative positions. It is understood that the terms so used areinterchangeable under appropriate circumstances such that theembodiments of the invention described herein are, for example, capableof operation in other orientations than those illustrated or otherwisedescribed herein.

Any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations merely illustrative. The multipleoperations may be combined into a single operation, a single operationmay be distributed in additional operations and operations may beexecuted at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

However, other modifications, variations and alternatives are alsopossible. The specifications and drawings are, accordingly, to beregarded in an illustrative rather than in a restrictive sense.

The phrase “may be X” indicates that condition X may be fulfilled. Thisphrase also suggests that condition X may not be fulfilled. Forexample—any reference to a pool cleaning robot as including a certaincomponent should also cover the scenario in which the pool cleaningrobot does not include the certain component. For example—any referenceto a method as including a certain step should also cover the scenarioin which the method does not include the certain component. Yet foranother example—any reference to a pool cleaning robot that isconfigured to perform a certain operation should also cover the scenarioin which the pool cleaning robot is not configured to perform thecertain operation.

The terms “pool cleaner” and “pool cleaning robot” are used in anautonomous manner and may refer to a self-propelled pool cleaner.

The terms “including”, “comprising”, “having”, “consisting” and“consisting essentially of” are used in an interchangeable manner. Forexample—any method may include at least the steps included in thefigures and/or in the specification, only the steps included in thefigures and/or the specification. The same applies to the pool cleaningrobot and the mobile computer.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims.

Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under”and the like in the description and in the claims, if any, are used fordescriptive purposes and not necessarily for describing permanentrelative positions. It is understood that the terms so used areinterchangeable under appropriate circumstances such that theembodiments of the invention described herein are, for example, capableof operation in other orientations than those illustrated or otherwisedescribed herein.

Those skilled in the art will recognize that the boundaries betweenlogic blocks are merely illustrative and that alternative embodimentsmay merge logic blocks or circuit elements or impose an alternatedecomposition of functionality upon various logic blocks or circuitelements. Thus, it is to be understood that the architectures depictedherein are merely exemplary, and that in fact many other architecturescan be implemented which achieve the same functionality.

Any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations merely illustrative. The multipleoperations may be combined into a single operation, a single operationmay be distributed in additional operations and operations may beexecuted at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

Also for example, in one embodiment, the illustrated examples may beimplemented as circuitry located on a single integrated circuit orwithin a same device. Alternatively, the examples may be implemented asany number of separate integrated circuits or separate devicesinterconnected with each other in a suitable manner.

Also for example, the examples, or portions thereof, may implemented assoft or code representations of physical circuitry or of logicalrepresentations convertible into physical circuitry, such as in ahardware description language of any appropriate type.

Also, the invention is not limited to physical devices or unitsimplemented in non-programmable hardware but can also be applied inprogrammable devices or units able to perform the desired devicefunctions by operating in accordance with suitable program code, such asmainframes, minicomputers, servers, workstations, personal computers,notepads, personal digital assistants, electronic games, automotive andother embedded systems, cell phones and various other wireless devices,commonly denoted in this application as ‘computer systems’.

However, other modifications, variations and alternatives are alsopossible. The specifications and drawings are, accordingly, to beregarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps then those listed in aclaim. Furthermore, the terms “a” or “an,” as used herein, are definedas one as or more than one. Also, the use of introductory phrases suchas “at least one” and “one or more” in the claims should not beconstrued to imply that the introduction of another claim element by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases “oneor more” or “at least one” and indefinite articles such as “a” or “an.”The same holds true for the use of definite articles. Unless statedotherwise, terms such as “first” and “second” are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements the mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

Any system, apparatus or device referred to this patent applicationincludes at least one hardware component.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

Any combination of any component of any component and/or unit of poolcleaning robot that is illustrated in any of the figures and/orspecification and/or the claims may be provided.

Any combination of any pool cleaning robot illustrated in any of thefigures and/or specification and/or the claims may be provided.

Any combination of any set of pool cleaning robots illustrated in any ofthe figures and/or specification and/or the claims may be provided.

Any combination of steps, operations and/or methods illustrated in anyof the figures and/or specification and/or the claims may be provided.

Any combination of operations illustrated in any of the figures and/orspecification and/or the claims may be provided.

Any combination of methods illustrated in any of the figures and/orspecification and/or the claims may be provided.

We claim:
 1. A set of pool cleaning robots for cleaning a pool, whereinthe set comprises a first pool cleaning robot and a second pool cleaningrobot that differ from each other by at least one unit out of apropulsion unit and a cleaning unit; wherein each one of the first poolcleaning robot and the second pool cleaning robot comprises a filteringunit, a housing, and a controller.
 2. The set according to claim 1wherein the first and second pool cleaning robots are configured toclean at least one region of the pool in a cooperative manner.
 3. Theset according to claim 1 wherein at least one pool cleaning robot of theset is configured to clean a sidewall of the pool.
 4. The set accordingto claim 1, wherein at least one pool cleaning robot of the set isconfigured to perform collision avoidance steps for preventing acollision between the first pool cleaning robot and the second poolcleaning robot.
 5. The set according to claim 1 wherein at least one ofthe set is configured to perform cable entanglement avoidance steps forpreventing an entanglement of a cable connected to the first poolcleaning robot with a cable connected to the second pool cleaning robot.6. The set according to claim 1 wherein a cleaning unit of the firstpool cleaning robot comprises a PVC brush wheel and does not include aPolyvinyl acetate (PVA) sponge brush wheel; and wherein a cleaning unitof the second pool cleaning robot comprises a PVA sponge brush wheel anddoes not include a PVC brush wheel.
 7. The set according to claim 1wherein only one of the first pool cleaning robot and the second poolcleaning robot comprises a sponge brush wheel.
 8. The set according toclaim 1 wherein only one of the first pool cleaning robot and the secondpool cleaning robot comprises a brush wheel that comprises a spongebrush wheel portion and a PVC brush wheel portion.
 9. The set accordingto claim 1 wherein the first pool cleaning robot is configured to removecoarser dirt than the second pool cleaning robot.
 10. The set accordingto claim 1 wherein the first pool cleaning robot is configured to hoverbetween a bottom of a pool floor and a waterline.
 11. The set accordingto claim 1 wherein the first pool cleaning robot is configured to skimthe water surface and then sink to the bottom floor.
 12. The setaccording to claim 1, wherein the first pool cleaning robot and thesecond pool cleaning robot are configured to clean different regions ofthe pool.
 13. The set according to claim 1, wherein the first poolcleaning robot comprises a detachable module, wherein the first poolcleaning robot and the second pool cleaning robot are configured tointerchangeably receive the detachable module.
 14. The set according toclaim 1, wherein the first pool cleaning robot comprises a detachablesensor, wherein the first pool cleaning robot and the second poolcleaning robot are configured to interchangeably receive the detachablesensor.
 15. The set according to claim 1 wherein the first pool cleaningrobot and the second pool cleaning robot are configured to clean a sameregion of the pool at different manners.
 16. (canceled)
 17. (canceled)18. The set according to claim 15, wherein the first pool cleaning robotis configured to perform a preliminary cleaning of the region and thesecond pool cleaning robot is configured to perform a supplementarycleaning of the region, wherein the preliminary cleaning is slower thanthe supplementary cleaning.
 19. (canceled)
 20. (canceled)
 21. (canceled)22. The set according to claim 1 wherein the first pool cleaning robotis configured to clean a slippery flat bottom region of the pool. 23.(canceled)
 24. The set according to claim 1 wherein the first poolcleaning robot and the second pool cleaning robot cooperativelyreallocate cleaning tasks according to failure to complete cleaningtasks.
 25. The set according to claim 18 wherein failure to completingtasks are failure to traverse slippery pool surfaces.
 26. The setaccording to claim 1 wherein only the first pool cleaning robot isconfigured to clean a slippery sloped bottom region of the pool.
 27. Theset according to claim 1 wherein only one of the first pool cleaningrobot and the second pool cleaning robot comprises a jet propulsionunit.
 28. (canceled)
 29. (canceled)
 30. (canceled)
 31. (canceled) 32.(canceled)
 33. A method for cleaning a pool, the method comprisescleaning a pool by a set of pool cleaning robots that comprises a firstpool cleaning robot and a second pool cleaning robot that differ fromeach other by at least one unit out of a propulsion unit and a cleaningunit; wherein each one of the first pool cleaning robot and the secondpool cleaning robot comprises a filtering unit, a housing, and acontroller.
 34. (canceled)
 35. (canceled)
 36. (canceled)
 37. (canceled)38. (canceled)
 39. (canceled)
 40. (canceled)
 41. (canceled) 42.(canceled)
 43. (canceled)
 44. (canceled)
 45. (canceled)
 46. (canceled)47. (canceled)
 48. (canceled)
 49. (canceled)
 50. (canceled) 51.(canceled)
 52. (canceled)
 53. (canceled)
 54. (canceled)
 55. (canceled)56. (canceled)
 57. (canceled)
 58. (canceled)
 59. (canceled) 60.(canceled)